Change levelup stat choice interface
s - same key used for waiting and saving by default
i - same key used for showing inventory or spells by default
d - same key used for dropping items by default
This means that players often accidentally raise the wrong stat because they leveled up right before trying to do one of those actions.
There are not enough comfortably reachable unused keys to simply change the keys used for stat choice - every letter and number is already used, although lowercase p is not, and so are ,<.>/?;:'"[{]}=!@#$%^&*()\|, Tab, Space, Enter, PgUp, PgDn...
So it would be best to change the interface for this altogether (or possibly the mechanic itself). Make the player confirm their choice with Y, perhaps.
Failing all that, strength is the worst offender because of mashing 's' and enter/space while monsters die to your allies or clouds. So at least require the player to press the uppercase letter, instead of accepting lowercase s/i/d.