I agree! I really loved the game and for me it was a little disorienting at first.
I don't feel you need to buy anything, but it would be nice if at the end of the game it said something along the lines of "you got 56/100 coins" or something like that.
I agree that it's a little confusing, I had to teleport around a lot before I could remember where I was, but usually in games I find I remember where I am pretty quickly. I think it's something called 'invisible design' or something like that, where you subconsciously map things in your mind. I love the idea of making thing mossier and more water-damaged the further you go down
I knew that the EMP canon was to the left, because thats the direction you were shot from , but I thought you had to keep going down until the water was drained, though that part was still a cool mechanic.
This game is really amazing for what it is and very professional looking. if the creator added these little things and made the game a bit longer with maybe a bit more plot I really think they could charge for it!
one more thing I would add: the name of the robot character! Id love to know the name of our little robot friend, and maybe the other aliens too.