Grappling Hook is a first-person action game somewhat in the style of Portal, in the sense that you must use the only device you own to navigate a series of rooms. In this case, it's the grappling hook of the title. The controls are simple: WASD and mouse for movement, though A and D are used to strafe, unlike in many other titles. You can also use Shift or the Space bar to jump.

The mouse button fires the grappling hook, which will only adhere to green-colored walls. You can fire the hook any number of times without actually grappling; you can use the hook to activate distant buttons, for example. You will only travel to the distant hook point by holding down the left mouse button.

The object of Grappling Hook is to navigate a series of rooms and exit by retrieving all "access codes" to get to the next level. These codes look like orange diamonds, and you pick them up by colliding with them. The upper left corner of the screen will always show how many you have to collect, and how many you've already collected. The bottom of the screen displays your health, which is rechargeable. You heal damage at checkpoints, which also save your progress within the level.

Right from the start, you get a pair of jump boots that allow you to jump higher than normal. Why the game makes a point of "giving" you these boots instead of just making that height the default jump is beyond me. Regardless, it is possible to take damage from falling, so that's a concern.

The environment consists of regular walls, floors, and ceilings, with certain modifications. Some walls and floors (and some ceilings) have orange arrows that point you in the direction you need to go to get to the exit. Some walls have green panels; these indicate the places you can grapple to. Some walls have a retractable set of panels; these are controlled by a button situated nearby. As stated earlier, these can be activated with a grappling hook.

Some floors are electrified; you take damage for as long as you stand on them. It usually takes only a few seconds to take full damage and die. There are no "lives" in Grappling Hook. You just keep going until you've made it through the level or give up.

There are also elevator floors that lift you, and walls that push. You'll need to use these to get around, which is a matter of timing. Mostly, however, it's the grappling mechanic that is the most important.

While traveling through the air on a grapple, you can jump off and let the momentum carry you. This is vital to master, as many of the later levels can only be negotiated via this tactic. The level that finally stopped me from continuing to play involved grappling, jumping off, and grappling to another wall while in mid-air, then riding that grapple's momentum to a distant platform, all above an electrified floor that didn't give me enough time to look back up to the ceiling to grapple again before dying. I had to finally give up in frustration, which is a shame because I was really enjoying it. Ironically, this was the first such first-person game that didn't make me simulation sick, which every other FPS has done.

If you're a fan of these kinds of immersive action puzzlers, give Grappling Hook a try. You can grab the demo right here on Big Download for both Mac and PC.