As a hormonal and tone-deaf teen I went to see Megadeth live. Despite my unfathomable love for speed metal with Sylvester the Cat-style vocals, their support act Pantera stole the show. I could only pity Megadeth for having to follow Pantera's aural sledgehammer of a performance and I feel the exact same kind of pity for Deus Ex: Invisible War - for it had the unfortunate task of following up a game that would come to be seen as a classic at a time when the technology or budget couldn't match the team's vision.

By now you've probably read or heard all about the first Deus Ex countless times in the build up to the release of Human Revolution. How it's a masterpiece, how it changed gaming, how Human Revolution has a massive legacy to live up and how Eidos Montreal's game better not be another Invisible War.

These days it seems that no one has anything good to say about the black sheep of the Deus Ex family. The mention of its name brings back old wounds for those who worked on it. Human Revolution's developers talked of the 2003 sequel as "a cautionary tale", a what-not-to-do lesson for their reboot of the franchise. Every mention of it on discussion forum involves sage nodding of heads and plenty of backslapping chat about just how dreadfully disappointing it was.

And they're right. I'm not going to argue that Invisible War is a better game than Deus Ex. That kind of talk would only end with me being carted off in a straitjacket. But despite its many mistakes, Invisible War is nowhere near as bad as its reputation suggests. In fact, in a few ways it's actually better than the original (and now I think might be the time to install that flame-retardant biomod).

For a start it's a better shooter than Deus Ex. For a series that prides itself on player agency the tricky gun play of the first game nudged people towards creeping around rather than allowing them to choose between being a sneak or acting like RoboCop.

Then there's the universal ammo concept. No more messing around rearranging ammo in your inventory like an obsessive compulsive - just one clip to rule them all.

Sure the execution wasn't spot on as nothing told you how much ammo each weapon would drain, but the basic concept certainly didn't do Mass Effect 2 any harm. There were also some great biomods like the nanobot spy drone that you could use to scout an area before piloting it up a military bot's rear end and letting it dissipate in an EMP blast.

That said, for every decent addition Invisible War screwed up somewhere else. It reduced hacking to waiting for a bar to fill up. Even worse, it then rubbed that in by robbing us of the joy of playing a nosy parker who gets their kicks from reading emails that provide tiny insights into life as a bored office worker from the future. The scale of the areas in the game is another bugbear, each seemingly squashed down to the size of a bedsit to help Invisible War to fit on the Xbox.

But some of the other criticisms levelled at the game are really questions of design preferences, like the controversial decision to remove the mixing and matching of the skills and augmentations that let you mould a JC Denton of your own design in the original. Instead of this freedom, Invisible War gives you a miserly five biomod slots to fill.

After the freedom of Deus Ex it felt as confining as the game's bonsai maps, but this restriction also made each choice more meaningful and important. Do you sacrifice the ability to regenerate your health at will in order to have the spy drone option? Invisible War simply decided you couldn't have your cake and eat it. And that's kind of fitting because Invisible War's morally ambiguous tale is rather bleak.

The opening sets the tone with the destruction of Chicago by a suicide bomber who unleashes a nanotech bomb that turns the windy city and its citizens into grey goo. For a game released at the height of post-9/11 fears about dirty bombs and Islamist terrorism, the topicality can't be missed.

Later down the line - and once you leave Seattle the game really gets into its stride - there are plagues caused by nanotech pollution, exclusive enclaves where the rich enjoy a pampered life while the rest of the population lives in shanty towns, and genetic purists who think nothing of killing children to further their cause.

And then there's the Omar - a sinister group of hive-mind cyborgs that echo the cybermen off Doctor Who. Their creepy, barely human personalities make you almost feel sorry for the arrogant Leo Jankowski when they decide he should join them in their blue frog suit club. Almost but not quite. Hell, even Tracer Tong now regrets his actions in the first Deus Ex.

On top of that you're not even really the hero, but a cipher being played by vying factions who want to impose their vision on the world. As such the endings you can choose are really a choice between the lesser of four evils rather than any world-saving glory moment. Games don't usually do bleak; usually there's a pat on the back for being a winner. Invisible War instead simply makes you question whatever reasoning you use to justify your actions.

Still there's always the secret nightclub finale if that's all too much. Although that involves something about flushing an American flag down the loo, so you'd probably just cause the Tea Party to rise up and who knows what they would be capable of in an age of biomodification.

It's not all bad. There's the amusing tit-for-tat competition between the Pequod's and Queequeg's coffee shops with their nanotech coffees that whiten your teeth as well as wake you up. And who couldn't enjoy the chats with the holographic AI pop star NG Resonance who moonlights as a police informant - guess that's what happens in a future where no one pays for music.

That said Invisible War's overall attempt at creating a truly malleable story didn't really work. It's too easy to shift allegiance at any point, which undermines the meaning of your choices, and you can miss important parts of the story by sticking to one faction too much.

Invisible War is destined to spend its future living in the shadow of the game that came before it and, now, the game that came after it. But there's enough Deus Ex pixie dust within Invisible War for it to deserve a better fate than being remembered for what it is not rather than for what it is.

Sheldon Pacotti, the video game developer who wrote the first two Deus Ex games, has revealed his indie game, Cell: emergence.

Cell: emergence, due out before the end of September on PC and the Xbox Live Indie Games platform, is based on voxels. You pilot a nanobot through the body of a sick little girl, melting infections with self-replicating colloids, building shields and pathways with buckyfibers, and shredding germs with monofilament daisycutter depth-charges. Or something.

"The visual style looks low-fi and even retro, but that is because the bulk of the processing is dedicated to a deep simulation that extends down to every voxel in the world," he told Eurogamer.

The game's mechanics are based on "dynamic voxels" - voxels which contain not just visual data but also game-state.

Arcade action is layered on top of a "cellular automata" simulation of the human body.

Pacotti's studio, New Life Interactive, has released a video that shows off the simulation. It's below.

"We assert that such 'massively reactive' mechanics could add life to the next generation of video games," he said.

"Massively reactive describes game mechanics that leverage massive processing power for game interactions, rather than just visuals," Pacotti continued.

Sheldon Pacotti is best known for co-writing the first two Deus Ex games – both won critical acclaim for their storytelling.

Video: