Once the game is solid enough, I think doing playtests and gathering player feedback helps a lot. Watching how people actually interact with the game often reveals things you’d never notice as the developer, and it gives a better idea of whether the experience is truly enjoyable.
Totally agree. We've been experimenting with running games through different simulated player profiles... like "how would a total beginner react vs a hardcore grinder vs someone who only plays 5 minutes at a time." It's been eye-opening how differently the same game lands depending on who's playing. Have you tried anything like that or mostly just watch people play?
At first I asked some friends to play my game. When they tried it, they had no prior knowledge about it, and they were different types of players. Some liked exploring, while others tried to reach the objective as quickly as possible. It’s not a large playtest sample, but even from that small test it helped me understand how different players approach the game.