Digger Chan
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# Digger Chan - (c) Aypok 2006 #
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What is it?
===========
"Digger Chan" is a game for the Sega Master System, very much like the game
"Mr Driller" - which was released on the Gameboy Advance (amongst other
platforms).
This game was written by Aypok for "SMS Power!"'s 2006 coding competition.
As well as the game binary and this documentation, you will find the full
source code and data-files for assembling this game. The code is released under
the GNU/GPL v2 (see the file titled "licence.txt"). There is also the tool I
wrote and used to create the levels. It is a simple Python script to generate
random levels based on some parameters given to it at run time. See the
section below (called "Other boring info") for more details.
I started work on the game in late February 2006, shortly after the
announcement of the competition was made. It took a few weeks of work to get it
done, but it was worth it. :)
There is no sound and no music in this game. None at all. Unless I made a
coding error which results in sound... Why? Two main reasons: I have no idea at
all how to make sound on the SMS (but it is something I wish to learn in the
future) and Mekanix won't run properly if sound is enabled (which seems to be a
common error).
I have not tested this game on real hardware - that is to say, this game was
developed using emulators to test the code. This is not out of laziness, but
because I lack the hardware to do so. While this game does run fine on the
emulators, I have doubts as to how well it will run on a real SMS. If anyone
gets to test it on real hardware, I'd be interested to hear how it goes.
Feel free to contact me about bugs in this game, ideas, improvements, general
feedback, etc - you know the stuff.
Please take note of the difficultly level; It starts off VERY easy. Too easy,
in fact. But it does get hard - play at least until level three to see what
I mean. Level five is amazingly hard... It took me two days to complete it
(without cheating) - and I know the level layout. :)
It is probably worth noting that this is the first game I have written for the
SMS. I've written a bunch of smaller things - nothing this large. I had to
learn a bunch of new things to get it done and it was great fun. :)
This is for a competition, so I'm hoping I win - although I'm up against some
very skilled people, so I'm not sure how that'll turn out. I've had a great
time creating this game - losing won't bother me much. It would be nice to have
written a "prize winning" game, though. :P May the best entry win!
I hope you have fun playing this game!
Aypok...
Story
=====
You are "Digger Chan", an employee of "M.O.O. Milk Co." - the world's largest
supplier of milk. Not only do they bottle it and sell it in shops, they also
have a huge pipe network which pipes milk from their storage facilities to
various places around the world: schools, factories, offices and even homes.
The customers love having milk on tap and get displeased when there are
problems with the pipelines which cut off their supply of milk.
This is where you come in - you are M.O.O. Milk Co.'s "digger". It is your job
to dig down from the surface to the milk pipelines deep under-ground. The
pipelines are so deep, normal excavators are useless - which is why they need
specialists like you.
M.O.O. Milk Co. have been very pleased with your work in the past, which is
why they will give you three tries to do your job and get to the pipes, If you
fail three times, you will be fired!
Basic info
==========
The object of this game is to dig down through the layers upon layers of blocks
and reach the bottom of each level. It's not as easy as it sounds... You only
have a limited supply of milk to keep you sustained during your exhausting
digging. You must find bottles of milk burried in the ground to quench your
thirst. As you progress through the levels, they get longer and longer - and
the amount of milk available for you to consume diminishes.
As well as the levels getting longer; the further you go, the more types of
blocks you will encounter. They are just as easy to dig through, but due to the
mixed up state of the ground, it will take you longer to make your way to the
end zone. Watch out for large chunks of steel and other pipes on your way down,
your spade isn't strong enough to dig through them - you must go around them.
Watch where you dig - you may fall into a deep pit! You can only climb up one
block at a time - some of the pits are two or more blocks deep. Digging without
looking where you are going is dangerous...
There are three different types of terrain for you to work in, since the pipes
span the world. As well as having to dig through normal ground in the city, you
have to dig through frozen ground in the arctic and sandy ground in the desert.
The arctic ice is very slippy - so be very careful when moving! The desert is
very hot, so your need more milk to keep you going, The ground in the desert is
very soft - meaning that you move a lot slower than on normal ground.
When you dig through a block, all of the connected blocks (blocks connected
diagonally do not count) of the same colour will also be removed. This makes
the progress through the early levels, which have just the two types of block
(red and green) easy going and rather speedy. There are four different colours
of blocks in total for city ground: red, green, blue and yellow. In the arctic
you get: white, purple and blue. The desert has: red, orange and yellow blocks.
Each block is one metre high, so the "depth" read-out refers to how many metres
underground you are.
If there are no blocks underneath a bottle of milk, it will fall down until it
hits a solid block. A lot of milk bottles are hidden under other pipes and bits
of steel, so you'll need to dig under the steel to get to the milk.
There are a total of seven levels in this game (the last three were cut):
level 01 - 50m - City (Very easy).
level 02 - 100m - City (Easy).
level 03 - 150m - Arctic (Medium).
level 04 - 250m - Arctic (Hard).
level 05 - 400m - City. (Medium).
level 06 - 400m - Desert (VERY hard!).
level 07 - 550m - Desert (Hard).
Even though it may seem like it, none of the levels are impossible, Tricky,
but not impossible. If you get stuck on a certain point of a level, look to the
left and/or right sides of the path you were taking - look for large clumps of
blocks of the same colour. Destroying strings of blocks allows you to fall
further and faster than destroying one block at a time - which is why the early
levels are easy. Beware: sometimes the path which looks the easiest is trapped!
If you keep getting stuck in a trap when trying to collect a bottle of milk,
pause the game and see what other paths into it you could have taken. Unlike
the levels, some of the milk bottles ARE impossible to get. :)
How to play
===========
Left:
Move Digger Chan left.
Right:
Move Digger Chan right.
Left Left: (Double tap)
Climb up. If you are right up against a block to your left, you can double
tap the left button and climb up ontop of it. This only works if the stack of
blocks to your left is one block high - you cannot climb up stacks of two or
more blocks.
Right Right: (Double tap)
Climb up. Works the same as a double tap left, but for the right-hand side.
Button 1:
Dig down.
Button 1 & Left:
Dig left.
Button 1 & Right:
Dig right.
Button 1 & Up:
Dig up.
As you can see from the controls listed above, not only can you destroy the
blocks lying directly underneath you, you can dig through the blocks to either
side of you - even the blocks directly above you.
Keep an eye on your milk-o-meter! If it starts getting low, make sure you grab
a bottle of milk to keep your energy up and your bones strong. If you run out
of milk, you will not have enough strength to continue and it will be the end
of the game... The milk is harder to find on the later levels.
Scoring
=======
For each block (of any colour) you destroy, you get one point. If you destroy
four or more blocks in one dig, you get one extra point. If you destroy eight
or more blocks, you get two extra points. Destroyings sixteen or more will earn
you an extra four points!
Collecting a bottle of milk will get you a whole ten points.
When the level is complete, you get one point for every ten metres you dug
through and five points for every bit of milk you have left. You also get a
1000 point bonus for completing the level.
You get an extra try every 2000 points. The maximum number of tries you can
have is nine.
Tools used
==========
Slackware Linux: OS of choice. :)
jEdit: For writing the code.
WLA-DX: Assembler.
Python: Writing the level generator and stuff.
BMP2Tile: For converting the two intro screens and the title screen.
The GIMP: Creating the two intro screens and the title screen.
KolourPaint: Editing the screens and prototyping some tiles.
Mekanix: Emulator used to test and debug this game.
Other boring info
=================
To assemble the game, simply type "make" from a terminal in the directory
containing the makefile. That will build a file called "digger_chan.sms".
The file called "useful_functions.inc" is the very same one used in Maxim's
tutorials on coding for the SMS - I have used it, unchanged, in this game.
There are also various bits of his code used in this game, most notably: The
code used to draw the blocks and the code to scroll the background. There are
probably other snippets in there, too. however, most of the code is my own.
Some of the graphics, with the exception of the intro screens, the player,
and the font, were written by hand - not drawn in a paint program and
converted... Several of the tiles were prototyped (designed) in KolourPaint
and were then converted by hand to code. The tiles/tile-map for the intro/title
screens were created with Maxim's "BMP2Tile" application, as was the player's
sprite.
Testing of the game was done with "Mekanix", the *nix version of "Meka" - an
SMS (and other 8bit Sega systems) emulator.
The code is released under the GNU/GPL v2, which means you can edit, change,
etc, the code for this game and redistribute it - but you MUST in turn make
your code open and free for everyone to use. For more details on the GPL,
please see the file "licence.txt". If you do use the code in some way, I'd
love to hear about it. :)
The code is, for the most part, heavily commented - so it should be easy to
follow and understand. Having said that, my coding style is sometimes viewed
as "odd" - sometimes it is down-right badly done. I don't claim that this
code is perfect, or even great - but it does work. Usually. :)
I created a bunch of Python scripts to help me convert and create data for
this game. Most are useless, but one is very useful: "map_builder_tiny.py".
It is a very simple script which builds level files (tile-maps) for use with
this game. The levels it creates are based on parameters passed to it at run
time. It is not as heavily commented as the game code, but it should be
very easy to follow - providing you're familiar with the Python language.
The level builder accepts parameters in the following way:
"python map_builder_tiny.py <file> <rows> [R] [G] [B] [Y]"
"<file>" is a required parameter and specifies the output file.
"<rows>" is how deep you want the level to be (in rows of blocks).
The last four parameters ("R", "G", "B" and "Y") are optional - but sort of
required. They specify which colours of blocks to use in the level. "R" is
for red blocks, "G" for green, "B" for blue, and "Y" for yellow. they can
appear in any order. For example:
"python map_builder_tiny.py test.inc 100 R G"
Will create a 100 row level (tile-map) called "test.inc", using only red and
green blocks.
It will randomly add in empty spaces and milk bottles - they cannot be
controlled via the command line parameters. The space at the top of the level
and the end zone are also added to the level file by this script. It is ready
to plug into the Digger Chan game (it will need to be reassembled for it to use
the new levels, though). The sides of the level are added in-game, to cut down
on the amount of data needed to be stored.
You will probably want to manually edit the level files after creation by this
script to correct the placing of the milk bottles. Their placing is random and
usually either clumps them together or places them too far apart.
The arctic and desert terrains only have three blocks. In the arctic: red
becomes white and green becomes purple - yellow is unused. In the desert: green
becomes orange - blue is unused.
All of the maps in the game were initially created with that Python script,
then I edited the position of the milk by hand and added in all of the steel
blocks and traps (also by hand). A very tedious and time consuming task (and
it makes your eyes hurt - try it!) - but it's the only way to get good levels.
Cheats
======
While there are no cheats built into this game, you can still cheat if you have
something to alter the contents of RAM whilst the game is running - Meka allows
you to do this. I will list a few useful RAM locations here with what they do,
so you can cheat your way through the game - or just get to see it all without
having to play through it. :)
A full list of RAM locations and what they do can be found at the top of the
main code file.
$c00e - Number of lives left.
$c010 - The larger of the two milk counters.
$c026 - The current level.
$c027 - Level complete flag. Set to 1 to skip the current level.
This bit isn't really a cheat, but... You can actually climb up into empty
spaces even if there is a block directly above you. For instance; if there is a
block above you, but a space to the right of it (your upper-right), you can
double-tap right and climb into it. This isn't a bug, it's more of a lesser
known feature. :) I could easily fix it, but it is useful for getting into
tricky spaces - so I'm leaving it in.
Todo
====
Although this has been released, it is not 100% complete - I had to leave
certain things out in order to get it done on time. These things were never in
my original specifications of the game (they weren't "chopped" from it), they
are merely additions I'd like to have made if I had more time.
After the competition has ended, I will still be working on it - adding in the
improvements I'd like to have put in originally. I will then release a new
version of the game when it is complete (which will be available on my site
and probably announced on the SMS Power! forums).
Here's some things which are hopefully still to come:
- Sound effects (and possibly music - but I'm not sure about that yet).
- Two player co-op mode (two players work together).
- Timed "fun" mode, where you have to score as much as you can (by
destroying blocks) within a certain amount of time.
- Semi-breakable blocks. Blocks which take several hits to smash.
- Power ups and extra items:
+ "Condensed milk" - drains more slowly than normal milk - but only lasts
for about ten seconds.
+ "TNT" - destroys all blocks on screen (except steel and milk) - doesn't
harm the player.
- Full compatability with real SMS hardware! That means sorting out all of
the VRAM timings and such.
- Clean up the code... Lots of things can be done better and more
efficiently.
Depending on how much is changed and how long it takes, it may end up as
"Digger Chan 2". :)
Thanks
======
- The developers of all the great tools used in the creation of this game.
- Bock for fixing a lot of the VRAM timings and giving good coding advice.
- Maxim for his great tutorials on coding for the SMS.
- Everyone at SMS Power! and the forums for their help and documentation.
- Sega for creating the SMS.
- Developers of "Mr Driller" for the idea behind this game.
Contacting the author
=====================
Aypok can be contacted at aypok )AT( aypok )D0t( co }doT{ uk, via his website
at http://www.aypok.co.uk/ or via IRC on the OdinNET network (irc.odinnet.ca).
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