Thanks for the detailed feedback!
Online multiplayer was actually something that I wanted to add but couldn't get working. I guess with online multiplayer, it's one of those things that you have to build your game from the ground up for.
I do think that an in game tutorial would have been nice - I tried to integrate the tutorial into the game by printing the hotkeys and displaying warning labels so that players could simply refer to them if they ever got lost, but I guess it can be a little information overload-y for a first time player.
As for UI, I thought that I sized all the text properly to stop them from showing up off screen, but I'll go back and check. It's also possible that different resolutions see tooltips differently.
Lastly, the sandbags were ironically one of my least favorite upgrades during playtesting. They usually inhibited my movement, preventing escapes and drop collection. But I guess I'm just unfamiliar with the way of the sand...
Anyway, thanks for playing, and I'm glad you enjoyed it!