Ah, this is about Dolmexica Infinite, right? I think you could get it working without the assets.js (in the simplest case just copying the assets.js content into the game.js since both are embedded at the same place in the index.html), then the files you still have would be:
- game.js, the javascript to run the game
- game.wasm, the web assembly
- assets.data the assets used by the game
I'm not sure if you can reduce it further. The web build uses Emscripten (https://emscripten.org/) which is a sort of compiler-to-web. I know there is a way to do non-web-assembly builds with Emscripten as described here (https://emscripten.org/docs/compiling/WebAssembly.html) but the last time I tried those to debug something, they didn't work with Dolmexica. It would be done by adding -sWASM=0 to the linker when compiling the game. That's not possible with the make-your-own-game kit since that one already has the linked version.
The current linking command used by all my games (even Inside that's embedded on this page) is in my web/dreamcast cross-development engine here: https://github.com/CaptainDreamcast/prism/blob/develop/Makefile.commonweb , the command itself starts on line 9, you would add the -sWASM=0 to that. But like I said, since it changes so much in the compilation and is more of a legacy option at this point, it will most likely just result in a black screen and probably some startup javascript exception unfortunately.
I'm not sure if you could get rid of the .data file either, from what I see here on the documentation about packaging (https://emscripten.org/docs/porting/files/packaging_files.html), it seems to be a necessary component.