When you beat a game, you usually unlocked new modes, new characters, etc. depending on the genre. For example, if you beat an action-adventure or platform game you could try to collect all of the same type of item to complete your collection. Play the same game again on a new difficulty you just unlocked or on a higher difficulty as a challenge in order to get good at the game and do some hard work on new game plus. For RPGs, you can max level up your party in Pokemon for instance and complete all of the quests. Beating the same game on a different difficulty ain't so bad and you could get good at the game that way.
Tip: Try out new modes, challenges, etc. after you beat the game.
Tip: Try out new modes, challenges, etc. after you beat the game.