How would one make a game that they're not good at playing?

First, don't make a game you're bad at. If you don't "feel" what makes this specific genre cool to play, you're very likely to fail to deliver something enjoyable. Why would you even want to? Hard work and stress for unrewarding result. Make something you like.

Second, if you for some unintelligible reason need to do a game you don't like (e.g. you're being paid money), water the difficulty down. People play hard games only if they get "hooked" on those. Everybody praises Mario for being difficult, but it's not because it's difficult, but because it's Nintendo and hype. They won't play a hard game from a no-name dev (if you don't have a team with QA, that's you), unless you somehow manage to pinpoint your specific audience and properly promote the game to them (but as you're bad at this kind of games, you aren't likely to, unless, again you have a PR in your team to do that for you). And eventually those players won't appreciate your game because you'll fail to deliver the "feel" they're after in this genre. Easier games appeal to a wider audience.

/r/gamedev Thread