First step there would be to get some logs. Launch steam from a terminal and output to a file:
<span style="color:#323232;">steam 2>&1 | tee steam.log
</span>
Launch a game and watch the terminal to see what happens.
If you moved games after launching them, clearing their Proton containers can help. I had some games set to extremely old Proton versions that couldn’t launch because the version jump was too big. I’ve also seen vanilla wine prefixes break when moved due to some symlinks.
But those are guesses, the logs will tell you. Sometimes it even actually tells you how to fix it!