Thanks for playing!
That visual bug and the lag of the web version are news to me, I will run some tests but I am honestly not sure what could be causing them.
The endless rotation is 'intended' in the sense that it isn't a bug, but I agree that it trivializes the game a bit. In the previous version I had a 'move counter' where after a number of moves/rotations, the Tetromino would fall down by 1 on its own. I should re-implement it.
The other problem you mentioned is also something I plan to address: aside from the fact that in the final game there would be a reason to want to collect as much loot and level up as much as possible before going for the exit (and thus, a reason to let the Knight move around), I want to add an 'enemy turn' when a tetrom- pentomino is placed. In this phase, all the enemies will take their turn and move across the map regardless of the knight. This, together with aggressive AI that actively looks for the player, should pressure you to actually move the Knight and fight enemies before you get surrounded.