What is a video game that you'd love to play, but no one has developed yet?

I really love, and really miss, healing in wow raids circa WOTLK through Cata, specifically using healnot and custom keybinds to keep people alive. I don't have time or budget for an MMO in my late 30s, nor do I see that easing up anytime soon.

I think a game where you had to do raid mechanics/puzzles while keeping NPCs alive through healing could be really fun, even without a loot grind. Or a game that dropped you into a multiplayer raid encounter without the crap around it. Either could be great.