Hello! Thank you so much for giving the game a try and for your feedback. I am very glad to see you enjoyed it overall, and I really appreciate that you pointed out some points for improvement. I completely agree that it should be easier to pick up items, and that the timer should alert you that time is running out a bit earlier than it does. I also agree that it would feel alot better to get rid of the invisible walls and make the map feel less square-like. Unfortunately I cannot update the game for the next month or so, because it was submitted for a game dev competition and it is currently in the judging phase, but I will absolutely try to find some time to update it once that is over.
By the way, I noticed that you did not use the teleport ability. That's triggered using the shift key. That would teleport you to your mouse pointer, and it would make it easier to get away from a mob of slimes!