In Ooops Up, you are a space traveller lost in space. You have to travel to 100 stars (or levels), to collect the necessary components to build a new space-ship, one that is able to get you back to earth.
The game plays a lot like the more well-known Pang. Each level is a single screen, and to complete it, you have to destroy some bouncing asteroids. If you touch one of them, or the time runs out, you lose one life.
Your weapon is some sort of harpoon, that can only shoot straight up. When it hits an asteroid, the asteroid splits into two smaller versions of itself, unless it's already the smallest variant. If that's the case, it finally gets destroyed. When all asteroids are destroyed, you travel to the next star. Repeat this 100 times, and your ship will be completed, and the game is won.
You can also get different bonus-items, such as a gun, time-stoppers, shields making you temporarily invulnerably, and other stuff.