I’m tempted to say that although many of these are gaming icons, they’re not PC-exclusive so they’re not really PC-gaming specific mascot material. Most of these characters are playable on consoles too.

I guess this makes MMORPGs and RTS games prime candidates, like a character from Runescape, Starcraft or WoW. Or perhaps something that shows off modding, like the Thomas the Tank Engine dragon (even if the game isn’t PC exclusive).

The Kerbals from KSP could be mascot material too. Dwarf Fortress would be an option too. Or what about a guest from Roller Coaster Tycoon 1/2?