Nice game ! As said in another comment, that's a really interesting concept. I love the emphasis in exploration, and the idea of having to choose the modules.
However, it was frustrating to have to switch between the solar panel and the wheels because there isn't enough space in the inventory. Depending on your ideas for your game, you could solve this problem in a few different ways : add more inventory space ; reduce the space of the solar panel ; don't have the wheels as a module ; allow to easily switch between modules with a key so you can swap in the middle of a fight, for example.
Also a few things I noticed :
- The sound effect for the charging battery is a bit too repetitive so you get annoyed if you leave the solar panel in the robot
- There is also a clipping sound when this sound effect loops
- If you accidentally click on your battery to move it, you're dead. Maybe a small internal buffer for the robot would be interesting to avoid that
- If you eject the wheels at anytime you won't be able to move, so you essentially lost.
Otherwise, it's very good and I'd be very happy to play an updated version of the game, a bit easier and with more content ! :)