I suppose it was inevitable, wasn't it? Pretty much since day one, comparisons between Wii U-exclusive Splatoon and early Team Fortress 2 have run thick, like wet paint or a rotting bucket of squid chum.
Both are fast, fun team-based shooters that eschew grimdark trappings in favour of cartoon whimsy. This mash-up TF2 mod by DrLilRobot and friends (they of that in-progress TF2 campaign mode from a while back), then, looks like it might be pretty fun.
The mod is still a work in progress, but it's already got the fundamentals in place. Paint, squids, teams and a fortress. It's lacking kids, but we've all got to grow up eventually. Perhaps Splat Fortress is also meant to serve as a rumination on the inexorable march of time. We live, we outgrow Nintendo and move to Steam and desperately struggle to bring popular Nintendo games to Steam in some form or fashion, and then we die. It's poetic, really.
At any rate, if you're dying to play Splatoon but don't have a Wii U, this looks like your best bet. I plan to keep an eye on it, for sure. Here's hoping Nintendo, um, looks the other way.