Callisto (Atari XE/XL)

Jason Kelk's Callisto, written for the ABBUC Games Competition 2012, has taken me back to a simpler, happier age of gaming. Come on, you remember: a time when you didn't need a tutorial to learn the controls of a new game, seventeen fingers to execute that elusive special move, or a degree in computer science to install the darn thing on your computer.

It's a sideways scrolling shoot 'em up: fly, shoot, dodge and weave. That's it. No pyrotechnics when you pull the trigger, no quadruple shot with plasma cannon and confetti power-up, no super-nukes or chain reaction mega-explosions.

You might describe it as a purists' shoot 'em up. Everything it does, it does smoothly and beautifully, but it is the genre stripped to its essentials. There are no power-ups or bonuses for destroying enemy waves, and there are no end-of-level guardians to defeat.

I think avoiding such shmup trappings is an astute piece of game design. Callisto is constructed in such a way that the avoidance of enemies and navigation of obstacles is just as important as destroying aliens or enemy craft. Introducing extra weapons would needlessly unbalance the game, and something like triple shot would be next to useless given the tight confines and tunnels you fly through. Besides, how many times have you played a game where you lost a life - along with your upgraded weaponry - at an advanced stage and found that it was next to impossible to get any further?

Callisto looks great, from the clean, crisp, rotating spaceships and aliens to the detailed scenery that scrolls smoothly along. Each of the four level designs is themed to a distinctive graphical style; you'll find yourself navigating cave systems, ancient ruins, an alien space station, and a weird alien world. These backgrounds are integral to the gameplay: they house laser installations, dictate the flight paths of enemy waves, force you to dodge and weave through narrow gaps, and offer a choice of routes. The further you go, the tighter it gets, and the faster your enemies spin towards you.

Jason Kelk has written on his blog about some of the technical challenges in programming the game and the tricks he used to overcome them. It is an interesting read, and certainly highlights that the hardware is not conducive to creating the slick, fast-paced shooter that Callisto is. The smooth movement of the dual-colour sprites and enemy waves, along with the excellent scrolling, become all the more impressive when the limitations on the number of objects on screen and the efficiency of the programming techniques used are considered.

The alien waves move in set patterns but are not necessarily predictable as they will suddenly change course or inject a burst of speed, until they are zooming around in dizzying patterns on the final level. Excepting the lasers - which fire in a regular pattern - nothing shoots back. But don't make the mistake of thinking that it is easy, as the laser gates and attacking spaceships combine effectively to make things tricky. In fact, the difficulty level and curve is just right. Callisto is a proper challenge, but you will never get irredeemably stuck and frustrated.

The title tune is very accomplished and zippy, and the sound effects are nicely understated and pleasing to the ear. The only disappointment in terms of presentation is the lack of any meaty explosions: all enemies are dispatched with an underwhelming pop. The ending of each level, and indeed the game, is also rather a non-event. I don't bemoan the lack of end of level guardians as if you get them wrong they can ruin a game by either being too tough or offering no challenge at all. But something would have been good: a target to destroy, someone to rescue, or a portal to fly through - even a particularly nasty wave of enemy ships to contend with.

One thing you will need is a robust fire button on your joystick. Each alien takes several shots and they do keep on coming. In fact, I would advise sorting out those auto-fire settings, unless you want some serious RSI.

Callisto is impressively smooth and fast to play and the collision detection is spot-on. Coupled with excellent presentation all-round it is a quality gaming experience and a serious test of skill. But despite enjoying its uncomplicated, minimalist approach, I can't help feeling that introducing the odd curve-ball like enemy ships that shoot back or rocket installations really would have got the adrenaline pumping. All the same, Callisto clearly pushes the hardware pretty hard and you certainly won't regret taking it for a spin.

Download the game here (from the Cosine Systems website).
Run it using Atari800Win Plus 4.1 (freeware).