Minor update, a few months ago someone on the 7chan forums was able to decrypt and unpack the 7.4 version of the game. The decryption means the game is fully and easily modifiable, and that, along with the unpacking, means the load time is significantly improved. I've linked the file along switching the load order to the data folder (by using a blank.pak file) which means you can edit the source files directly without having to pack and unpack them every time you make changes.
Mega
Important to note, the game uses v3.0 of the OpenBOR game engine. The wikia page linked below provides a convenient overview of how the engine works.
You must be registered to see the links
One last thing, the boss rush mode doesn't work in this version due to it searching for files that do not exist. I made a working mode that goes through each boss, along with some minor edits like infinite lives (since cheats are tedious to activate), and also the removal of timers, and less loading images and animations. If anyone is interested, I can post that file as well.
Anyways, have fun with the game!