The Mini-Ludum Dare for this month had the theme of Demakes so I decided to create a version of Coffee Quest as it would be had it been created or ported to the Atari 2600. The link is http://blazinggames.com/gamejams/2014/MiniLD50/ but it is going to be my April game. That means it is time for a postmortem.
What went right
For rendering the 3D view, the program emulates the play field graphics of the 2600 by having a function that takes the pf0, pf1, and pf2 registers along with 3 alternate values for the right side of the screen. While writing the rasterizer as if I was really coding for the 2600 took a lot longer than I like, it ensured that the resulting game was actually something that could run on the machine. For me, the whole purpose of this challenge was to create a game that could actually run on real hardware. With a bit of work, it would be quite possible to create a full-fledged RPG along the lines of Coffee Quest IV on the 2600. Sure, the graphics would not be that great and a pretty big cartridge would have to be used but it is doable.
While the rendering is done the way it would have been coded for the 2600, the map is not. The map is 32x32 bytes which is far too large. If this was coded properly, the map would have been broken into a wall bitmap (which would have only taken 128 bytes of ROM) with an additional 16 bytes to hold the coordinates of the objects. The time taken getting the renderer working made this impractical so I went with a traditional tile map approach so the game could be finished over the weekend. As I know my reduced memory approach will work, this is not that huge of a deal as the game is clearly still possible.
What went wrong
I simply did not have the time necessary to create this game for the 2600 so had to roughly emulate the limitations of the system. Having researched the 2600 before starting this project, I found the limitations of the platform really intriguing so was sad that doing this project for real hardware (or at least a properly emulated version of real hardware) was not practical. The problem is justifying the amount of time that would be required to create this game on a 2600 emulator. Even considering that modern tools allow for much greater efficiency in creating the game, I suspect that it would take at least a solid month of work to finish this game. With no real way of recouping the value of my time, this project is sadly not worth doing. If enough people were interest (or if someone was willing to sponsor the game) then I might reconsider this project. So, if anybody wants to see this project running on a 2600 emulator, email me at spelchan at blazinggames dot com and let me know.
Next week, partly as a continuation of this topic and partly to demonstrate how different machines can be when it comes to assembly language, I will be going over the Hello World program that I wrote for the Atari 2600. Just quickly going over what is required to do that simple program will give you much more respect for those poor 2600 programmers.