Remember Undertow? No? Shocking. Undertow was the game Microsoft gave away free in January 2008 as a way of saying sorry for widespread Xbox LIVE connection issues experienced the previous Christmas. We gave it a 7/10 - the simple side-scrolling 2D shooter providing a decent amount of fun in an underwater, Geometry Wars kind of way. And, since it was free, it was better than a kick in the groin. Well, Crash Commando is PSN's answer to Undertow, except, well, it's not free. It's £7.99 to be exact.

You control a Commando, as you'd expect, using the left thumb stick for movement and the right thumb stick for aiming, with R1 reserved for firing. L1 is used to fire your jet pack, which propels you upwards in a floaty fashion. There's limited fuel, meaning you can't keep yourself in the air for ever, but it does recharge. Running and floating about the eight maps and shooting other Commandos till they pop in a gory poof of blood and guts forms the crux of Crash Commando's gameplay. And it's actually quite a lot of fun.

The maps themselves are divided into two types: Standard, which are large; and Showdown, which are small. Each map has two "layers" which are navigated by passing through tunnels. You can actually see the other layer, and players battling within it, in the background, which is a nice touch. At the beginning of every match, and before you respawn after death, you get to choose your load out. There's plenty of weapons, each with their own strengths and weaknesses. The basic weapon, the machine gun, is a decent mid-range weapon with good power and quick reload. The shotgun does what all shotguns do in games. There's a sniper rifle, which makes the straight line aiming sight much longer and, if you're good enough, will one-shot kill, a grenade launcher, a rocket launcher and the CAB, which can heal allies as well as damage foes.

The weapons act as a class system of sorts. In fact, Crash Commando is a bit like Valve's excellent online shooter Team Fortress 2, with similar weapons and an over-the-top, almost cartooney art style. There are two vehicles, a fast-moving rail buggy, which has a machine gun turret, and a slow but powerful tank, which can run over on foot enemies. There are a couple of turrets, too, which can be sat in and used to shoot enemies jumping about in the other layer, as well as randomly spawning super weapons which give you a temporary god-like status.

The action is fast and a lot of fun

Supplementing all of that is a nice bonus system which rewards you for staying alive. You're able to select, with the d-pad, from three bonuses - one grants health regeneration, one gives you a speed boost and the other gives you the Death Spin attack. Survive long enough and you're able to get all three bonuses at once.

Game modes are divided up into deathmatch, team deathmatch and objective types. The deathmatch modes do exactly what they say on the tin, but the objective modes require a bit of explanation. Here one team attacks and one team defends. In Sabotage, one team must blow up three control panels with bombs, the other team defend and diffuse them. In Espionage one team must download four lots of data and bring them back to their base. The other team, as you'd expect, needs to stop that happening.

The action is fast and, despite the floaty nature of the Commandos, the controls feel tight. The weapons work well and the gory pop of enemies when you kill them is immensely satisfying. Using the tank and mowing down loads of enemies in quick succession provides the most thrilling moments in the game.

Online multiplayer is where this game shines

Although the game comes with a single-player component, called Boot Camp, it's clearly been built for multiplayer, and it's here that Crash Commando is at its best. Up to 12 players can play online, and, while we struggled to fill that quota with real life people during our tests, the game fills in the gap with mindless bots. If you can get a game full of real people, though, Crash Commando proves to be an accessible, fun, fast 2D arcade shooter. The different weapons imply a class system and the bonus system implies strategy, but really it all boils down to who's best at aiming and shooting. That's fun in of itself, so it's no big problem.

So, is Crash Commando worth £8? If the gameplay appeals, then the cash is just about justified. A lack of a local multiplayer mode is a shocking omission, the audio is instantly forgettable (it's a predictable military score), and the single-player mode is boring as hell. But the online component, when you get a game with real people, provides great fun and the Team Fortress 2-style weapons and art style should appeal to most. Better than a kick in the groin.