Stuff you'll likely be editing:
lib/definitions.js- Tank, bullet, and all entity data.config.json- Map data and other options.server.js- Everything else, like movement, AI, firing, stats, damage, spawning, etc.!
Stuff that you probably won't touch:
lib/fasttalk.js- Data compression. No need to change it.lib/hshg.js- Deals with updating the game grid.lib/random.js- Contains all the random functions. Also contains the randomized Bot and Boss names, if you want to change them.lib/util.js- Miscellaneous functions.package.json- Nothing to edit here, just stuff the client uses to run the game.