Dice - hit 6x 5 times in a row
Limbo - hit 10x 4 times in a row
Scarab - hit 900x in free spins
Hilo - win a bet with A,10,J,Q,K not consecutive but skipping is not valid
Plinko - hit 420x then 620x in same seed
Blackjack - win a bet with 2 aces
This would take some time to hit but a challenging suggestions 🙂