So plowing through many different games on e.g. Steam, and just playing each game for a short period (not trying to excel or improve your scores) before moving on to the next game, could somewhat satisfy #1 and #2 (novely + challenge)?
It might also be important to play differently challenging games (#1), e.g. DotA2 + Europa Universalis 4 + CS:GO will give you a much wider spectrum of brain training than going through the japanese RPG catalog.
That said, constantly seeking novelty is not good for your grit score, which seems to be a better predictor for 'success' than intelligence.