It wasn't the first time I played Dungeon Adventure with my three year old, but Sunday's adventure was definitely the most successful. I think three year olds can have fun with Dungeon Adventure, especially if there's an older sibling or friend to help out. We tried an interesting variant where we threw hit points out of the game completely. Each battle consisted of rolling to see who won the fight. If the player rolled higher, they won and it was over. If the monster rolls higher, the monster wins that fight and the player must do some sort of physical activity to simulate the rigor of combat. We agreed upon 10 jumping jacks.
Most battles ended quickly at the start with the occasional jumping jacks thrown in for bad rolls. When harder monsters appeared with roll bonuses, my kids seemed to get lucky rolls and won those, too. The final battle was another story. Both Owen and Sasha both had trouble defeating the Giraffe Snake with his +2 to attack. They must have done 100 jumping jacks each before I finally rolled a one. They were so exhausted after the fight they almost forgot to open their treasure (2 hershey kisses!).
In this variant, treasure food obviously didn't restore their HP but they enjoyed them anyway. There was a party dispute when Owen opened the first treasure chest and ate 3/4 goldfish crackers. His 6 year old sister and fellow adventurer was NOT pleased, but in the end they saved Pokey and a princess and had a blast.