The remake of Age of Mythology plays great on it. I've also played Age of Empires I & III Definitive Editions on it a lot, but that required a significant amount of steam controller profile tinkering, and it's only good for slower single player turtle play.

A recent story game I played fully on it was Ys X Nordics. Great action and story game and tons of fun, and ran pretty well on Steam Deck. Ys VIII Lacrimosa of Dana also played well on it and is a long but incredible story, and Ys I & II Chronicles. All great story driven games I've played on Deck. I'm sure the other Ys games on Steam probably will also be good on Deck.

Some other good options I've played a lot on Steam Deck:

• The first Warhammer Space Marine game
• American Truck Simulator
• Warhammer Inquisitor Martyr
• Sniper Ghost Warrior 2
• Metal Gear Solid V
• Halo MCC, I played a lot of Reach and Combat Evolved on it
• Metal Gear Rising
• Just Cause 2
• V Rally 4
• Shadow Tactics
• Mad Max

These I've also played tons on Steam Deck, but I think they required some tinkering to get running:

• Elder Scrolls Oblivion (not the remake)
• The Saboteur
• Warhammer Dawn of War 1
• Sacred 2 Gold
• Renegade Ops