The tactic of flipping the gravity on the player, whether by giving the player the power to do so voluntarily or forcing it on them as a stage hazard, has been around for a pretty long time in video games. I'm not sure if it was the first, but as near as I can tell, Irem's Metal Storm for the NES was one of the earliest games to use this mechanic, allowing you to reverse gravity at your will. After that, it was seen here and there, but it seems to have really made a comeback thanks to VVVVVV. Fans of mobile games are no stranger to it, of course, thanks to games such as Gravity Guy [$0.99] and Gravity Duck [Free]. TripTrap [$0.99 / Free], an interesting little stage-based action game, uses a variation on this tried and tested technique as its primary mechanic.
You play as a little mouse named Ched, apparently short for "Cheddar", which seems a lot like naming your kid "Chicken Wing", but I digress. He sets out in each stage to collect three pieces of cheese and safely make it to the exit door. In total, Ched will run through four areas of the house, each with their own unique and dangerous hazards. Being a mouse, there aren't too many moves at Ched's disposal. He'll automatically run forwards at all times, with extra abilities to run forward faster and jump to a parallel surface assigned to buttons. If he runs into anything dangerous, you'll have to start the stage again, which isn't really that bad since every stage is built around a single screen.
There are 80 stages in TripTrap, and while the game starts off very simply, it introduces new tricks along the way to keep the difficulty moving up smoothly. At first, you'll just be running around a stage with no hazards and three pieces of cheese with no gimmicks at all, but by the time you reach the end, you'll have weathered cat-bots, cheese that expires if you don't reach it in time, one-way traps, and deadly electricity, to list but a few. Most of the action in the game simply comes down to timing your hops, but another major aspect is in controlling the direction Ched's running in. Some doors and pieces of cheese can only be approached from one side, and certain hazards will always move in a fixed direction.
TripTrap has two modes, casual and puzzle, with the difference between them being that puzzle mode restricts the number of jumps you can use to clear each stage. None of the stages are all that difficult to clear in casual mode, though getting all of the pieces of cheese is sometimes a little tricky, but the puzzle mode definitely requires a good plan and careful timing. Cheese is used to unlock each set of stages, but the requirements aren't terribly high, so even if you're having trouble getting all of the cheese on some of the levels, you'll still probably be able to move forward. I think even if you're the sort that just wants to clear the levels and call it a day, you'll get a good value out of TripTrap with its initial allotment of stages. The puzzle mode uses the same stages as the casual mode, but the jump restrictions make them feel like quite a different challenge.
For fans of score attack games, you might also find a little surprise in this game. You're scored on each level based on a number of factors, with Game Center leaderboards in place for each set of levels. People in our forums have been competing a bit on them, though the presence of an IAP for a helmet to protect you from obstacles does seem to be dampening the excitement a little. The developer has expressed that they're going to try to adjust for that situation in a future update, so the game could still hold some potential in this regard. Speaking of IAP, in addition to the helmets being sold in various quantities, there are also IAPs to unlock areas early if you don't feel like unlocking them on your own. As I said earlier, the requirement for unlocking each set is pretty low, so I can't see too many people needing to go the IAP route here.
The presentation of the game is really good. Ched oozes with personality thanks to little touches of animation here and there. Sure, cartoon mice have been done in every which way, but I like the little guy. The game opens with a really well-done short animated cut-scene, setting up the tale of Ched's hunger plight with style. Even the hazards take on a bit of personality thanks to brief animations that play out should Ched run into any of them. The backgrounds are perhaps not as interesting as you might expect given the stages being named after rooms, but their subdued palettes and spartan details ensure that the important elements stand out. The music is pleasant if not memorable, evoking the same classic animated feel the graphics aspire to.
The App Store definitely has its fair share of these stage-based affairs where you're trying to collect or earn three things, and if you're dead sick of those, TripTrap probably isn't going to be the one to change your mind. If, however, you like the sound of that gravity mechanic and aren't fully exhausted with the concept, you'll probably have a good time with the game. Score attackers should keep their eyes open for that update, as well, because if the helmets are somehow accounted for, this could prove to be a lot of fun to compete with friends on.