I wish I knew....I did go to here and DD 2.5 loves the PreK-K (4-5 year old) games and some of the 1st grade ones. But there just aren't that many.
http://www.pbs.org/parents/earlymath/Click on age group pic and then select games on side bar.
DD fav is the sandcastle one, she is also adding how many sandcastles they are as she completes them even though the games do not do this....but you can help make them more difficult by doing this.
HTH.....Plus if anyone have anything else definitly let e know...DD is very into starfall and this pbs, we are still looking for others....I would even buy a computer game if someone can recommend one.