As we all know, XRun probably doesn't get as much attention as it should do, however I think this is partly due to the fact that it can get repetitive and boring when you play it, therefore people leave and the game hides in a little corner of CubedCraft for a few days. But, to combat this, you should probably add more interesting maps that aren't too difficult to complete and can be completed within a short amount of time, in order to keep the player's attention. Currently it is setup where the maps last for 5 minutes, but for most players, these maps can be completed at least twice within that time, which just seems quite boring to me.
Another addition would be to have different modes for each round. So for example: one mode could be getting the fastest time possible (the current and only mode) and another could be a like a race, where the one player wins by getting the finish line first. Another example could be completing the run with the lowest deaths. These are just suggestions, but I definitely think these would improve the game and possible attract more players to it!