Really interesting one.
Visually cohese and it's nice to customize the rig.
Music feels fitting, although the hit effects could feel more powerful (the missile ones are cool though!).
In my first run I didn't understand much of what was happening, took me a while to shoot enemies because the build button was clicked and I couldn't shoot. It was also hard to understand the delivery rules, first I went to the echo station but couldn't do anything there. On my second run I noticed that the first cargo was the blue-ish one. It would be nice to have some other hint of what can be delivered where, I could see differ the blue and the white one, but the other ones looked the same (sucks being color blind).
I had a situation in which I fell from the rig but while still kept in it, as shown in gif. It soft locked the game for me as I couldn't move, although the rig carried me through one last trip to the echo station. Here is me under the rig shooting, unable to move. sands delivery.gif
One of missiles kept on spinning around at one point, I think it targeted a desert cockroach that died too soon, so it just stood there spinning around its dead body. Looked nice though.
The crosshair kept on juddering, it doesn't affect the experience but visually it's quite annoying. The player laser could have started slightly later to not appear behind the gun, but that's just me nit picking.
Overall a really cool game! I like the setting and the customization, congratulations!