While the secrets of time travel still elude our understanding, reality hasn't stopped this tantalizing concept from appearing in dozens of video games. First-person shooters, role-playing epics, puzzle platformers, and arcade racers have used time manipulation to fuel creative gameplay mechanics from simple do-overs to complex historical changes. In Zeit Squared (written with a superscript "2"), the ability to rewind time briefly is just one of the various mechanics that make this shoot-'em-up uniquely challenging. The typical goals of "shoot everything" and "dodge a million bullets" are downplayed in favor of being frugal with projectiles, choosing how and when to eliminate certain enemies, and boosting your score and destructive power by interacting with your own time shadow. It may take some time to fully grasp all the mechanics at work in Zeit Squared, but once you do, fulfilling the many challenges and striving for leaderboard greatness become an engaging trial. And with plenty of different modes offering distinct twists on the core action, this refreshing and satisfying shoot-'em-up has a lot to offer.
You control your small shining ship as you fly steadily to the right, surrounded by a blue bubble that serves as your shield. The size of this shield is dependent on where your health is on a scale of 0-200 percent; the healthier you are, the bigger your shield. While projectiles only harm you if they hit your actual ship, any enemy that collides with the shield explodes and damages you. You die when your health is depleted, but enemy projectiles and collisions aren't the only way to lose health. Most enemies glow blue, and whenever a glowing enemy flies past you and out of the screen, you lose health. Firing your main gun also drains your health, but killing enemies returns some health to you. Managing the ebb and flow of your health is one of the biggest challenges in Zeit Squared. Letting enemies slip by you and shooting constantly drains your health very quickly, while maneuvering nimbly to target and blast your glowing foes is the best way to keep your health up.
Most of your enemies, with a few notable exceptions, do not actually shoot projectiles. They merely fly at their own pace in the opposite direction of your ship (or straight at your ship, depending on their behavior). Killing them earns you points, and earning a high score is one of the main goals in Zeit Squared. Destroying consecutive enemies increases your score multiplier, but if you let any enemy escape you, your multiplier takes a hit whether they were glowing or not. As you struggle for health and points, you begin to understand the core challenges of Zeit Squared. Moving around the screen and blasting frequently is an effective way to kill enemies, but the health you waste through prolific shooting may or may not be offset by the health you gain from killing enemies and collecting the occasional health power-ups they drop. You only need to kill the glowing enemies to stay healthy, but if you let the non-glowing ones slip by, your score suffers for it. The common shoot-'em-up challenge of dodging everything only crops up when you encounter enemy turrets, mines, or bosses, but these threats appear in less than half of the Arcade mode levels. Instead, your goal is to be quick and accurate enough to destroy your enemies without jettisoning too much health.
While this goal may seem simple, it doesn't take long before your enemies come at you in patterns that strain your maneuverability past its limits. This is where time travel comes into play. You have the ability to rewind time for up to 4.2 seconds--a reserve that regenerates slowly with time and can be replenished with power-ups that enemies drop. You press a key for as long as you would like to rewind time, and when you release it, time resumes. A shadowy version of yourself replays the section you just rewound, and you are free to perform whatever other actions you like. One simple yet effective tactic is to fly to the bottom of the screen and unleash a torrent of projectiles; then, you rewind time, fly to the top of the screen, and fire some more. This allows you to decimate two columns of enemies at opposite sides of the screen that you would otherwise be unable to simultaneously destroy. You can also double up fire on an enemy to destroy it more quickly or let your shadow destroy some baddies while you nab a helpful power-up.
While these fairly straightforward uses of the rewind are very helpful, there are a number of elements that make things more complex. Some enemies can only be destroyed while your rewind shadow is active; others are invulnerable during this time and must be eliminated during normal flight. A target circle appears to mark the end of your shadow's path, and if you are there when your shadow disappears, you earn a big score bonus. If you shoot at your shadow, your projectiles multiply and radiate out from the shadow in all directions, and if you shoot it enough times, you can trigger a shockwave that destroys all the enemies onscreen. Furthermore, as you earn powerful special attacks, you can use them in conjunction with your shadow to make them even more devastating. On top of all that, you can fast-forward time, which--though not as tactically complex as rewinding time and creating a shadow--offers big point bonuses and factors heavily into some of the gameplay variants.
This all may seem like a lot to take in, and initially, it is. As you play through the 16-level Arcade mode, you lose your running score every time you die, but you can continue indefinitely. You can get accustomed to the health maintenance and enemy-destruction basics fairly quickly, but the subtleties of boosting your score and maximizing your time-manipulation abilities take longer to master. Each play-through makes you better at anticipating enemy waves, slicker in your maneuvering, and more artful in your use of time manipulation. Zeit Squared is not a game you're likely to master right away, but as you become more and more comfortable with its complexity, you'll see your scores climb higher and higher on the online leaderboards. This tangible reward is a nice complement to the natural satisfaction of improving your skills, and once you are confident of your skills within the straightforward Arcade mode, there are six other variations that test your skills in different ways.
Score Attack is the simplest of the variations. You select a specific level, choose what special attack you want to equip, and then strive for a high score. Survival is also fairly self-explanatory, pitting you against an endless number of enemies and ramping up the damage they deal until you die. Wave mode also throws endless enemies at you, but in addition to death, an enemy reaching the left side of the screen ends the game. Killing enemies closer to the right side of the screen gives you bigger point bonuses, so memorization is particularly helpful. In Tactics mode, memorization is paramount. These levels are often less than 20 seconds and feature a specific deployment of enemies. Once the enemies hit the left side of the screen, they respawn on the right side, having transformed into another enemy. Of the two forms each enemy takes in Tactics mode, one is worth more points, so figuring out the best order to kill your enemies in is the key to success. Finally, Challenge mode sets certain scenarios for you to complete, like using certain powers in a given mode or killing a high percentage of enemies on a given level.
Even though Arcade mode is the backbone of Zeit Squared, the different variations offer an intriguing variety of ways to flex your abilities and explore the game's unique mechanics. The challenges of staying alive, killing enemies, and boosting your score are elegantly interwoven, as are the shooting, rewinding, and fast-forwarding abilities that you must master to succeed. Though Zeit Squared does draw on some of the common elements of the shoot-'em-up genre, it feels fresh and distinct. It's unfortunate that the visual design isn't more varied and vibrant, but it never presents a barrier to your success. Zeit Squared is an invigorating take on the reflex-and-skill-based action that makes the genre so exciting, and though it may take you a while to get the hang of things, the rewards are well worth it.