Also, it's nice on a subtle level in that you're effortlessly moving up in the world (or in to space, really). Nice for a leisurely play, but replayability is pretty low.
Surprise bomb rain was a bit annoying at first, but this game is really easy. Just stay in one of the bottom corners and click-drag bombs into other bombs that are coming down on you. When bomb rain comes, you only need to really clear 2 bombs (drag one into an adjacent one). Upgrades make it even easier. Super relaxing as I've hit 155080m, completed 28 missions in about 30 mins.
 "Zilch"){kind=icon}
 "Elona Shooter"){kind=icon}
 "Higher!"){kind=icon}
 "You Only Live Once"){kind=icon}
 "BridgeCraft"){kind=icon}
 "Pwong 2"){kind=icon}
 "Typing Ninja Hunter"){kind=icon}
 "- Music in Motion -"){kind=icon}
 "Fold"){kind=icon}
 "Manifold"){kind=icon}
 "pacman mouse-version"){kind=icon}