Gameboy Development Forum

Quite a few fairly sizable levels here! I just got the speed-boosting powerup.

I noticed the ROM is reasonably sizable at about 250 KB. I'm guessing a big chunk of that is the level data? Are you using any sort of compression for the levels? Meta-tiles? Or is it just stored raw?

I don't know how much more you intend to work on the game, but something I would recommend is to try to cut down on the number of blind jumps to places where there's moving monsters but you have no real way of knowing whether or not the monster will be at a safe point in its patrol until it's too late.

Last edited by DonaldHays (2016-08-30 21:42:52)

Isn't it nice how with modern hobby Game Boy programming it's generally fine if your game's data just barely bumps you up into a higher storage tier? We don't have the economic constraints to worry about that professionals back in the day did. "If I can't squeeze it into this smaller size, the carts are going to be X dollars more expensive to manufacture." I kind of chuckled at the thought when I added high-score battery save to my Snake game. I'm only storing six bytes: four for the word "SAVE" for integrity-checking, and 2 for the actual score. And that was fine. But if the game was developed back in the Game Boy's prime and was destined for a physical release I would have had to justify the added expense for the on-cart RAM and battery.

For making map data smaller, there's a couple of common techniques. Look into Metatiles (an extra layer of definition inserted between tiles and maps, where metatiles are arrangements of smaller tiles, and then your map is built as indices into a metatile table instead of indices into a tile table) and Run-Length Compression (instead of storing tile/metatile indices one-for-one, you pair a `count` with an `index`, and then decompress the map by writing out the `index` from each pair `count` times. So your stored data is like, "one of Tile 1, one of Tile 2, five of Tile 3, one of Tile 2, three of Tile 3", and that decompresses to "12333332333").

Also, I beat the game! I like that there was a decent number of levels, that stood out to me. Going into it I only expected one or two levels, so it was nice when it turned out there was more than that. Also awesome to hear you wrote it in assembly. And that you ran it on a Pocket! As a child I wanted to make Nintendo games, so I understand how rewarding it is to finally see your work running on hardware.

Just because I like reading these sorts of stories: have you got any interesting anecdotes about your experience developing it? Any awesome breakthroughs, neat tricks you implemented, or really tough bugs you spent a long time struggling with?

Yes, it is cool when you suddenly find the correct code to stream in tiles to the background map. Took me a while to figure it out, but I found something that streams tiles on the horizontal axis (not perfectly, the wrong tiles are loaded sometimes, but it works good enough for a reference point for me).