Mine is vehicle building games like Stormworks or Scrap Mechanic. It’s so much fun to shoot at your friends with your latest nuclear drone while hiding in your bunker with a better defence system than Area 51 !
I’m very curious about your fav niche game genre !
(I’m sorry for my bad English ^^')
“Simulator” games are surprisingly deep I have noticed. Power Wash Simulator and House Flipper are really fun and I’ve logged quite a few hours in both despite never pay attention to the genre before.