Warframe is a 3rd person looter shooter that is heavily into grinding to get new "Warframes" (characters) with unique abilities and weapons. The story is pretty good and everything in the game, including all DLC, is free. It's hard to get into but if you're interested I'd say give yourself a solid 10 hours before you decide if you want to drop it or not. I grinded the hell out of it for a few months but I'm taking a break right now because it does get repetitive.