In first picture, the brown thing as a too much low res texture. Same thing on next pictures , the meteorite don't have an enought detailled texture for a FPS view and game !
Why not increasing the resolution , or bringing normal map or baked detail texture ?

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For the levels instead of throwing simple 3D objects like that, you should make real concept draws , Google on internet
for gravity ideas and pictures, elements !

And you should really think in terms of strategy, to avoid a
simple jump and gun with gravity !
Somewhat like the bad oldf FPS : Quake Wars; where it was only players doing jump and gun like bunnies : AWFULL

So you could perhaps think in terms of bonus, strategie, tactics using gravity , if it is the main originality on your FPS !

Some ideas from scratch to inspire you :

The most important i think would be :
- Gravity affecting bullets would be great also :
A player would be shooting in a zone, and would be winning
against nother almost, suddenly the gravity would come back in that zone , affecting the player shooting that could not be as precise ! The player that would be loosing for example had catched meanwhile a bonus givinghim and it's bullet's no gravity effect for some seconds : What would give him a big advantage now !

After taht here is some other ideas !
- Little rounded planets where you could jump from one
to another in a level (Mario Galaxy style)
- Closed environement , like connected rooms, or unique rooms
with only one or two gates (entrances or automatic doors)
where gravity would be normal or different ?
- Tunnel or tubes (connected or not)
- Gravity zones (perhaps some indicators like colors, shader etc ... ) to indicate the direction of the gravity !
- Switches to invert gravity on these zones
(just play Mario Galaxy)
-Bonus to boost anti gravity (more speed and more control
over the gravity going on the zone)
This would forces players to try to reach these bonuses to
win bigger advantages
- Zones where gravity changes each time
- Example Bonus: Gravity inverted
- Boots or Jetpack allowing to not be so affected by gravity


Just to say you can make something really new, and polish it later, but planning gameplay, bringing new ideas, putting stratie , tactics, originality is really necessary if you want to make something not so standard !

Keep it up