Cant describe it.
Its a whole other level of gaming.
You gotta try it to understand.

But be warned, it will take more than 4 hours to understand it well enuff to enjoy it.
Give it at least 100 hours before deciding to abandon it and don't be shy to ask questions and google it.
It is VERY complex and the story is sooooo deep. its amazing.

imagine a third person shooter and a mmorpg had a baby and that baby evolve to include parkour.

Basically, you start with 1 warframe (choose 1 of the 3 starters) and you work your way around the solar system (multiple planets each with many maps) to complete quests, side quests, missions, challenges, assasination contracts and collect warframe and weapon parts to garnish your arsenal.

You can own all the frames if you're dedicated enuff and same goes for the dozens of dozens of weapons.

when you enter a mission with 3 other players, you enter with:
- 1 warframe which has 4 abilities (different on each warframes)
-1 primary weapon
- 1 Secondary weapon
- 1 melee Weapon
(each of those, weapon and frame, have 10 mod slots to customise em to your liking (more energy, more hp, more range, more damage, etc))

It does take a few hours to get used to the concept because there is just soooo much to do and nearly no tutorial but once you understand the basics, you can sink hundreds of hours in it and still haven't done all there is to do. Especially since they keep adding new stuff.