I have a 4 and a half year old daughter who enjoys playing games. We've played Ingenious with her before, but obviously she's at a huge disadvantage, so the wife and I had to throw the game.
She asked to play this again the other day and I wondered how we could implement a simple handicap to make the game more challenging for the wife and I and give the little 'un a more sporting chance.
Very simple really:
The child's score markers start higher up the score track.
For our four year old, we tried starting her markers on 5. This can obviously be varied based on the age/experience of the child.
After playing it this way, it turned out to be a very good balancer and I only just managed to beat her, with my wife coming last. Importantly, our four year old really enjoyed playing since she could play a grown up game with mummy and daddy.
We still assisted her slightly with the final placements of tiles. We let her choose the tile to play (sometimes we suggested the colour that she had the least of as a guide) and let her place it. We'd sometimes then tweak it's position slightly to maximize points. I'm going to put this assistance aspect down to her only being four years old. I imagine older children may fair better at this without assistance.