It's been mentioned a few times already, but I'd have to go with:
1. Bad grinding. The grind can be good. Grind can make sense, given certain contexts. Most of the time; however, the grind is unbearable. There's no reason anyone should have to repeat the same conversation with the same text twenty-two times so that they raise their relationship level from 10 to 22, and, miraculously, suddenly get on the slip-n-slide-ride. It's even worse when the Dev takes it personally when people cheat to avoid these shenanigans and implement "anti-cheat" measures in their wank game.
2. Recycled plots. We've seen it and been there a million times. You're at a college, you're a dick, you're out for revenge, you got a crazy powerup and now suddenly everyone wants to ride the balogne pony. There's nothing inherently wrong with these popular plot points, but more often than not people do the bare minimum in terms of innovation when they do use them. I've had plenty of instances where I download a game and fifteen minutes in I swear I've played it before, but it just happens to run the exact same plot of something I played in the past on the exact same engine.
3. No proofreaders. I'm mostly kidding, I respect anyone who's creating a game and translating from their mother tongue to English. Even as a native speaker, I know it isn't easy, and trying to get a proofreader to stick around unpaid or for very little is difficult, but it's rough finding a game I think I could really enjoy if it wasn't for the fact my brain keeps picking apart every single mistake to the point I can't focus on anything but the glaring engrish. This makes me tired in the sense that it's just unfortunate when I run into it.
4. The illusion of choice. There are so many Ren'py games that advertise them as a story where you hold the reigns, then you end up being cornholed into relationships with characters you're not interested in or decisions you'd never logically make in a million years, and I get it, you can't please everyone. But there's frequently been instances where there's simply no choice in the first place, you just get two choices that lead to the same outcome.