"Inversion's" single-player campaign, which was on display at E3, made good use of the gravity gimmick, but enemies and weapons failed to distinguish themselves.

To stand out amid an increasingly crowded lineup of first- and third-person shooters, it’s almost necessary for any new title to have some kind of gameplay gimmick. Get it right, and you’ll have the next “Portal” or “Bulletstorm.” Get it wrong, though, and you’ll end up with something like “TimeShift,” Saber Interactive’s 2007 shooter that revolved around the main character’s ability to manipulate time. Don’t remember that one? It’s OK. You’re not alone.

Saber’s next project, not counting its role in remaking “Halo: Combat Evolved” for the Xbox 360, hopes to succeed where “TimeShift” failed. Like its predecessor, it revolves around a cool gameplay concept; this time, it’s the manipulation of gravity. While a single-player hands-on at E3 and a more recent multiplayer session have served as solid proofs of concept, I haven’t yet seen anything that’s elevated the game to must-buy status.

“Inversion’s” story is centered around a character who takes up arms against an invading alien force. The central weapon in his arsenal is the Gravlink, a device that essentially lets him alter gravity within a small area. If an enemy is hiding behind cover, you can zap him with low gravity and make him fly into the air. If he’s running toward you, you can hit him with high gravity to slow him down. The Gravlink can also be used to throw objects at enemies, like the “Half-Life” games’ Gravity Gun. Addtionally, some of the levels feature multiple centers of gravity, so that you might walk into a room and see enemies walking on the walls and ceiling, while you’re on the floor.

Though there are some cool ideas at work in “Inversion,” the implementation thus far could use some polish.

Hourglass mode has players battling for control points on a map. When one side seizes the control point from the other, gravity reverses and the map is inverted.

Loosely speaking, “Inversion” is a third-person shooter with tanklike controls reminiscent of what you might find in “Gears of War.” You’ll generally be lumbering through levels, taking cover and popping out to shoot enemies, in between bouts of gravity manipulation.

At a recent multiplayer demo in San Francisco, I tried two of the three available multiplayer modes, missing a standard deathmatch game type. What I saw was intriguing, even if it felt far from ready for primetime.

The first mode, Hourglass, had two teams battling for a control point. It’s a common multiplayer game type but in “Inversion,” when a team takes control of a defender’s zone, the level’s orientation flips upside-down, and the defenders are now forced to attack to try to flip the map back to their orientation. What’s more, a handful of the areas on the map are zero-gravity, meaning you can kind of jump and shoot your way through them “Dead Space”-style.

“Hourglass” isn’t a bad idea, but “Inversion” didn’t really communicate during the match why the two sides were fighting over the map-flipping control points. I wanted there to be some kind of meta-game going on where, say, some members of the team needed to hold the map’s orientation a specific way so that teammates could accomplish some objective that hinged on a particular gravity orientation. In other words, controlling gravity should have been a means to an end, rather than the sole point of the mode. Instead, it felt like we were simply fighting over points on the map for the sole sake of controlling them. “Inversion” wouldn’t be the first game to include a standard king of the hill-style multiplayer mode, but Saber seemed to be wasting an opportunity here.

Additionally, Hourglass mode was so plagued by lag and framerate issues, it eventually became impossible to play. This is the kind of thing that typically gets ironed out before release, so it’s not a huge point of contention, but it was unusually bad and bears keeping an eye on.

Of the two "Inversion" multiplayer modes I tried, Survival was the more polished.

The other mode I tried, Survival, felt immeasurably more polished than Hourglass. A three-stage variation on the now standard horde mode, it has players fighting waves of computer-controlled enemies until, eventually, a high-powered boss enemy appears. Once that boss is defeated, a new area of the map is unlocked for players to enter. Once there, the process begins anew. Each of the three areas you’ll be fighting in are timed, with your unused minutes carrying over to the next area. If the clock hits zeroes before you’ve completed your objectives, you lose.

Survival has its heart in the right place. Instead of fighting intensely in one area for a great length of time like you would in a standard horde mode, players eventually get to move onto something new. That said, survival mode didn’t really make much use of “Inversion’s” gravity-altering aspects. Sure, players could use their abilities to force enemies out of cover with low gravity, but it felt largely extraneous to the core gameplay. I may have simply been doing it wrong, but the Gravlink seemed largely useless against the bosses, save for the ability to use it to grab objects and fling them.

Additionally, one other area in which survival mode was lacking was in player feedback. We could see the timer for each stage counting down, but the game didn’t relay any information to players about how many more waves of enemies we’d need to fight off before the boss appeared. It felt sort of like being given new goals at work, only to be told that the exact nature of the goals would remain a secret.

“Inversion” has some cool ideas under the hood, but with its Feb. 7 release date fast approaching, time to fix stuff will soon be in short supply. The multiplayer modes I tried could use more polish, and the bit of the single-player campaign I tried at E3 featured fun gameplay ideas but somewhat forgettable art direction, writing and weapon design.

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