Geometry Wars: Retro Evolved

On a basic level, Geometry Wars: Retro Evolved is a graphically improved version of the Geometry Wars mini-game that you could unlock in Project Gotham Racing 2. In it, you fly a little spaceship thing around a grid with the left stick and direct laserfire from it with the right stick, Robotron-style. The idea is to hold off the unending wave of enemies that spawn around the grid in incrementally larger groups. While being all graphically improved. Obviously. Just look at the way the grid ripples! They had to use a whole CPU core to compute that. That's how much they love you. And all those explosions. It's fireworks city and you're the mayor!

Enemies don't fire back, but that's no relief - instead they try and strike you head on, and if they succeed you lose one of the three lives you start with. Beyond that, you also have three smartbombs, which can be used to wipe out a screen full of enemies during a moment of panic. Stocks of lives and smartbombs are replenished at intervals of 75,000 and 100,000 points respectively.

It's incredibly simple, and owes a lot of its charm to this - whenever you load the game, you start from the same position, and anybody with two thumbs can pick it up without any kind of instruction. It is, with the possible exceptions of Zuma and Bejeweled, the most accessible Xbox Live Arcade game - but it boasts hidden depths that put the others to shame.

Obviously enemy numbers do ramp up, but there are specific patterns to their arrival - one in each corner, a stream in each corner, a variety in each corner, and so on - and each enemy boasts a particular attack behaviour. At the most basic level, little spinning windmills circle aimlessly while diamonds follow you around gently, gradually increasing in speed the longer they're left alive.

Then there are purple rectangles crossed from corner to corner, which hone in much more directly and quickly and, when struck, split into a pair of smaller rectangles that don't move toward you so quickly but do spin around in little circles to evade your fire. There are greenies, which race after you unless you're facing them, and dodge your fire if it comes at them any way besides straight on. There are purple-headed snakes, which squirm around but can only be wiped out with a shot to the head. There are little red devils that can move incredibly quickly in a straight line and have a front-mounted shield to deflect laserfire, but pause at the end of a run and can't do anything if you blitz them from the sides.

And then there are the swarms - bluey crosses that don't pursue you, especially, but test your ability to cut a clear path through them, and brightly coloured tiny blobs that mass out of the death of a black hole.

Black holes - red rings of darkness that spring up from time to time, and often several at a time - aren't really enemies, but they're not quite allies either. Once struck with a bullet or nudged by an enemy, they do the black hole thing and form an intense gravitational pull which affects the movement, to a lessening degree, of virtually everything within a large radius. On the one hand, they help you avoid becoming overwhelmed, which is handy - and by priming them and moving close to them, you can actually use them quite deliberately in this manner. On the other, they don't actually bank you any more points than you'd otherwise gain if you do try and work with them, they have a potentially unhelpful effect on your movement too, and they can eventually explode - and the eruption of swarming blobs is tricky to handle.

It's this kind of double-edged subtlety that you enjoy learning and marshalling as you play. At the lowest level, the interchanging weapon styles - there are three available, and you change at intervals of 10,000 points. More enduringly, score multipliers - with certain numbers of ships dead, your multiplier increases, up to a maximum of ten for 2000 ships destroyed in one burst. Lose one of your own and you go back to 1x, so, given the way the waves ramp up, it's usually best to try and get as much points-value out of your first life as possible. Smartbombs don't affect your multiplier, which is either a good thing or a bad thing depending how masochistic you are.

But while all of these things are good reasons to like it, the reason it continues to entertain is that it's been designed to be played with, not just beaten. And of course you can't beat it - it's a high-scores game, and theoretically never-ending. But while it's a constant upward ramp, it's not just a case of pushing slightly further every time; there are distinct breaching points, after which the rate of points-accumulation, and consequently life and smartbomb accumulation, increases. For quite a while it'll prove a real stretch to reach 500,000, but once you do you may find that a million's closer than you imagine.

It's not just about high scores, either. Like all Live Arcade games, there are worldwide and friends-focused leaderboards to compare your scores (and you certainly will), but the achievements here aren't that bad either. I find a lot of the 360 achievements to be quite tedious, mechanical, or, worse, disproportionate to the task completed; Geometry Wars does something that very few have done and doesn't just reward you for doing things in the game, but thinks of ways of playing the game and rewards them. Hence 10 points for "Pacifism" - surviving the first 60 seconds of the game without firing a shot. The others are more familiar - high scores, high scores on one life, maximising life and smartbomb counts - but Pacifism is as good an indicator of the design philosophy here as anything. If anything, it's just a pity it didn't go further.

It feels a bit churlish to complain about this sort of thing in one of the system's cheapest games - 400 Microsoft points is half what a lot of the new releases cost - but there are reasons to do so, not least the freebie PC rip-off Grid Wars 2, which looks and feels largely the same as Geometry Wars and also makes some interesting changes - encouraging you to experiment with black holes by multiplying the score much higher than Geometry Wars will, and cutting off your multiplier for using smartbombs, being the main things.

Amongst the more competitive of my 360 owning chums, there's also sour discussion about the differences between playing the game in 4:3 and 16:9 aspect ratios. Apparently there's something advantageous about doing it in the former, which has rankled for some. Thankfully for the final score, I left my anal retention with my other sphincter.