As if SRB2P wasn't crazy enough of a custom game mode, you just go and create an MMORPG.
Even playing this in its beta state, it was a super fun time as well as incredibly impressive to witness on the technical side of things. The choice from three vastly different gameplay styles, as well as a loot system, buying and selling stuff, even rare drops keeps the gameplay fresh and downright addicting. It's so satisfying coming back from a mission and mass selling all the stuff I don't use for my current run/class, keeping the stronger gear or even choosing to keep slightly weaker ones just to have element diversity.
Enemies having their own unique combat abilities also makes for downright threatening encounters with fish of all things. And the bosses are very intimidating when they can wipe you out easily with a few mistakes from your side. I really like how, even if you die in a mission, you can still go back to the latest checkpoint and keep going. Of course, it affects your rank, but it's still a really good thing to have.
I haven't even beaten a full campaign yet, I've only really got to the third set of missions and even then it was super engaging. This mod is a MUST with multiple people, though - running around with a squad of diverse team members (or funnily enough, 6 shadows with guns) is really, really fun. I've had such a chaotic time fighting a boss while my team members kept dying and me trying to revive them all the time, while also dying myself.
My only honest critique is that the gameplay can sometimes feel a little slow, but I grew to manage it and appreciate its slower pace, even though sometimes I wish I could pull off a DMC combo on a poor crawla.
A fantastic mod, can't wait to join massive servers with gun-sword wielding maniacs. Welcome Aboard!
I don't officially support the Android version as its specific quirks make it hard to maintain, sorry.