While there are different game modes, the gist of the Splatoon games is to cover the arena with as much of your team's ink as possible. Most of the mechanics involve spreading or interacting with your ink. Since you mentioned emulation, I guess you only have access to the single player campaign, so just follow what the NPCs tell you.

@ModernRisk

don't really know if you're able to play online with emulation, but with splatoon I recommend just going with the single player story until you figure it out. I don't remember it having much of a learning curve to start it.

there's a bunch of platformers I think are better than odyssey but are 2d, Celeste, Donkey Kong tropical freeze, both of the ori games

tho since you're able to play peakbot!!!