Set me a challenge in a video game?

>no counter strike

Try finishing all the side quests in Skyrim. I think thats a pretty good challenge.

Skyrim: Pacifist challenge. Play the game without killing any living thing. Between stealth and spells, it's very doable, but it does make you think outside the box.

Inquisition (or other DA or ME game): Evil challenge. Make all the cruelest and most selfish choices, kill/alienate as many of your companions and allies as you possibly can. Bonus if you romance someone and then break their heart. This works for youtube because you will get dialogue and scenes that few people manage to unlock.

I didn't read the list i just scanned through it and i didn't see this but you can try pokemon nuzlocke challenge.
basically you play through any pokemon game but with a twist
1. You can only catch the first pokemon you encounter in an area. And only one! Example: i run into a wurmple on route 101 i can only catch it or run away. But if i do run away or fail to catch it, this does include if the pokemon roars, teleports or any other kind of method, i have lost that one opportunity to catch that pokemon or any pokemon in the route
2. You must nickname every pokemon you catch
3. If a pokemon faints it is considered dead meaning you may not use it ever again. Either you release or box it in the pc (make your own dead box)

that is the slandered nuzlocke challenge
obviously there are different types if you just search on youtube

another locke i would recommend you doing and you can only do this on a pokemon 3ds game is the wonderlocke. Which means after catching one pokemon from that particular area you must wondertrade it

have fun