Woa, you really did an incredible job finding everyone's caches! I'm happy you enjoyed the game this much!
About the floor: you got me! The floor isn't really infinite because it was the first thing I made in the game, and at that time I wasn't sure on how to handle its real-time generation. Therefore, it isn't procedural, but it spawns from -10k to 10k. You actually discovered the end of the world! (well, the sky is infinite, and since it grows in every direction, the world itself is infinite too)
Apart from the floor issue, you've left me with some improvements to do. First, I need to implement a "Max score" system to record each player's best score, as he may lose it if another player steals his caches. Surely, the score that counts is the current one (which goes up and down), but having a souvenir of the best score a person ever had would be nice. Another thing I need to define is how to deal with every cache being too far (like they are right now), as new players won't be able to find anything at all unless they put a lot of effort into it.
About the compass: yeah, that's difficult to handle, specially with screens being so different. I have some ideas for improving the UI (and also for the compass itself) that I may implement in the future.
Thanks a lot for playing and for the feedback!