Since you didn't specify whether a flash game or anything else, PC or console, I'm free to overwhelm you with an entire catalog of options. But not to spam, if you played some games in the distant pass and liked them, here's a thought; replay some of them!
I'm currently playing both Devil may cry 4 and resident evil 4, both legendary games with a high enough replay value to make you come back for more. So if you have a game that you loved playing back in the day, dust it off and give it a go.
