It really depends on the game.
RPGs tend to be 40+ hours, going into the 100s sometimes.
How much of that is spent actually playing?
How much time can be deducted running back and forth on a map?
How much time can be deducted from random encounters? Waiting for your turn?
How much time can be deducted from all the text you read?
The same applies to SRPGs like Fire Emblem and Advance Wars.
A lot of time is spent reading, waiting for turns, watching animations if you don't turn them off.
Meanwhile more action-y games tend to be much shorter.
Platformers, hack n' slash, FPS', etc.
These are all much shorter, but there are fewer gaps between times where you're actually playing.
Both types are fun, but calling a 20 hour action game short compared to a 100+ hour RPG is a silly comparison.
RPGs tend to be 40+ hours, going into the 100s sometimes.
How much of that is spent actually playing?
How much time can be deducted running back and forth on a map?
How much time can be deducted from random encounters? Waiting for your turn?
How much time can be deducted from all the text you read?
The same applies to SRPGs like Fire Emblem and Advance Wars.
A lot of time is spent reading, waiting for turns, watching animations if you don't turn them off.
Meanwhile more action-y games tend to be much shorter.
Platformers, hack n' slash, FPS', etc.
These are all much shorter, but there are fewer gaps between times where you're actually playing.
Both types are fun, but calling a 20 hour action game short compared to a 100+ hour RPG is a silly comparison.