The spoiler boss in dead cells.

The boss is not particularly hard but you can only face him after a full run on the max difficulty where you will likely use most of your very limited resources before the bossfight, meaning you can only take a couple hits (at best) before dying.

A new redout game that is capable of mantaining a community would be great.

I think fighting games would make a good community, maybe with friendly tournaments organized regularly. The free ones that i know of are the hololive one (idol showdown) from steam and the emulated arcade titles from fightcade.

Monster hunter world. I bought it to have a replacement for genshin and it worked a little too well. It just feels different from any other game for how many things it does so well: from enemies to armor design to music to mechanics to weapon variety, everything is amazing.