I like the concept, and the title screen looks really nice (that onion planet looks delightful!), but the gameplay felt a bit lacking. It felt like I was just walking in a straight line, sometimes shooting a box or an onion, until I wondered if the stage was looping. And I went the wrong way at first, so I walked down this really long corridor with constantly repeating obstacles just to find a locked door! I didn't want to walk back so I just jumped in a pit, which teleported me back to the ship instead of killing me.
I don't know if that colored my perception, but walking back and forth multiple times - I think 6 or 7, as I managed to die partway - in complete silence just wasn't fun. There wasn't enough variation in the obstacles, and while there was some kind of boss at the end, I ran into it by mistake and then it just kind of left. Any time I hit a wall I'd jump into the nearest pit just so I wouldn't have to backtrack, so I never fought the boss at all.
I applaud you for having achievements people can strive for, that's a nice replayability feature for those who want it! I just wish the areas were either shorter or more varied.