To me, this seems like a game with a lot potential that just slightly misses the mark. The main gameplay loop and crafting/upgrading system is very promising, but in practice the game just doesn't feel all that fun.
I'd say this mainly has to do with the lack of threat and motivation. A 12 minute marker at the beginning of the game is just a bit too much, especially for a rather repetitive gameplay loop. That together with the fact that the levels increase only very slowly make it so that after a few minutes, the game starts to feel stale.
That being said, I think that some small tweaks could improve the experience a lot. Some suggestions are:
- reduce total time / time between levels. You could try breaking the total time up into sub-counters, where e.g. you have multiple rounds of two minutes to gain as many points as possible.
- Add more elements to the game, such as obstacles or enemies that gradually appear, making walking around more of a challenge.
- The addition of power-ups, a boost meter that slowly builds up, etc.
But then again, this is of course just one opinion, so feel free to do with it whatever you want!