Thank you for the wonderful comment! I'm glad you enjoyed it. I definitely plan to keep working on the game and make it a full-size adventure.
I thought a lot about allowing players to bump into each other, but decided not to do it. The main reason is when I play the New Super Mario Bros. games with my kids, they get frustrated when they're trying to do well and happen to bump into someone else, causing them to get hit or die and lose their powerup :D
I do plan to add checkpoints to the game in the near future so that you can respawn mid-level, especially in single-player where you can't respawn at another player's position. I also plan to add the ability to save your progress as the game gets larger.
Thank you again! It's really nice to hear that you found everything felt so polished!