Developer Hexage has been busy carving out an interesting space in mobile gaming over the past few years. The first title that hit our radar was Everlands for Android, which was a colorful tabletop strategy game. The later entries from this company took a much more minimal approach, which Robotek HD inherited for this iOS release. The graphics are done in a retro style that will remind you of the great Atari arcade titles like Battlezone. There are only minor changes from scene to scene as you progress in Robotek HD, leading to some potential for design-fatigue to set in.

Although the art is very basic, it shows the same cute aesthetic that Hexage uses so skillfully in other titles. The premise of the game is that you’re playing as a mainframe computer, battling other mainframes and their robot sidekicks. Other than the robots, most people would have a hard time characterizing a mainframe as a protagonist. Instead of dull boxes sitting in data centers, these mainframes appear occasionally with pirate hats and swashbuckling attire, and their compatriots are robots drawn with plenty of personality. Robotek HD is just round after round of trading attacks, so what keeps you entertained are the sights and sounds of your powers, and the reaction of your robots. Each attack has a distinctive sound, and robots will visibly flinch or react when struck. It’s simple and repetitive, but it works as short-term entertainment.

There are two distinct games here. One is a free, one-player game that showcases the battle mechanic, and allows you to progress as far as you’re able through the game world. Imagine a Google Map, with dots around the world highlighting battleground cities. Robotek HD is set in the days after the fall of humanity, and each city is the home of a particular mainframe responsible for overthrowing its human overlords. You start off battling the puny ones, whose hit points are low. Your goal is nothing short of world domination, which you’ll accomplish city by city. The tools at your disposal are robot sidekicks you can summon, as well as a few offensive and defensive tricks up your sleeve. The mechanism for using these against your enemy is... a slot machine?

Yes, the slot machine mechanic is at the heart of Robotek HD, but don’t let that dissuade you. The relatively limited set of skills, combined with the slow speed of the first slot, means you have a 100% chance of choosing one slot and a decent chance of making a match in the second or third slot. More on that in a bit. The in-app purchase aspect of Robotek HD opens up Multiplayer, a Duel Mode, and the ability to battle for experience without losing the energy points that are used as currency in the game. If you like the free play experience, it’s well worth your investment to open up the two-player action, but a careful (and lucky) player can get far with the free version. There’s limited replay value once you defeat all the mainframes, especially if you haven’t upgraded to the paid version where you can be matched against human players online.

Each city node in the world of Robotek HD is graded according to the energy required to battle in that location, and the relative strength of that city’s resident mainframe. Especially if you’re intent on playing the free, single-player version of Robotek HD, it’s wise to pay attention to these ratings. You can stockpile energy and buy your way into a city where you’re entirely out of your league. Robotek HD will warn you when you’re about to take on a mainframe with more life points, but an added element is how more advanced mainframes use better strategy. In the low-level fights, you’ll find disjointed attacks where a mainframe will leave itself exposed or make stupid decisions. It’s not rock-paper-scissors so much as tic-tac-toe, in the sense that one player can gain a major advantage if his opponent makes even one stupid decision. The element of luck is always there, but you learn how to gain and retain an advantage over time.

Later in the game, and if you’re battling human opponents in Duel or Multiplayer modes, you’ll find yourself perfectly matched from a strategy perspective. At this juncture, Robotek HD comes down mainly to luck and your tolerance for risk. Special attacks like the Unmaker Omega are only obtained if you manage to spin three matching slots. The odds of this are slim, but aggressive players may go for gusto rather than use turns to shore up defenses and repaid robots. Attacks like Hack, that convince robots to switch sides mid-battle, can quickly turn the odds based only on a percentage of success each time the slot stops on this ability. It’s this random quality that makes Robotek HD fun, compared to a perfectly predictable set of attacks and defensive maneuvers.

Spinning the slots sounds pretty relaxing, doesn’t it? Robotek HD delivers very casual gameplay, draped around a decent turn-based strategy game. Each turn consists of tapping to stop the slots from turning, after you pick one of three categories. The first category summons one of three types of robots. Each robot has a unique strategic advantage, mainly aligned with the tank/ranged/fighter axis we know well from action games. There’s roughly a 20% chance you’ll spin two of the same type, giving you a more powerful robot. You have a 10% chance to spin three of the same, which gives you the most powerful robot, and earns you a second spin. This model holds true for defensive tactics like putting up shields or draining an opponent's energy, and offensive maneuvers such as the Microwave ability that penetrates shields and causes collateral damage.

Robots that survive multiple rounds grow stronger, so there are plenty of special extras in Robotek HD that will keep you playing. As mentioned, we wished for more variety in the visuals, at least from continent to continent. Hexage is at least consistent in its presentation, and there’s room for additional content in the form of special codes (or in-app purchases) that grant you costumes and powers. The free game is a teaser, so if you like what you see in the first five minutes, it is well worth the investment to upgrade to the full version.