As another year rolls by, another game inevitably appears in the CSI franchise, the forensic-detective game based on the popular TV series. The latest is CSI: Deadly Intent, and developer Telltale Games are back at the helm for the new entry, after heading up 3 Dimensions of Murder and Hard Evidence (then missing a turn for the bizarre casual spin-off experiment CSI: NY). Could it be that Telltale have used the experience from their generally excellent episodic series to breathe some fresh life into a formulaic, repetitive franchise? Have they crafted a game which will delight CSI fans and adventure enthusiasts alike?

No. No they haven't. Unfortunately, Deadly Intent is crushingly turgid and boring, even for fans of the series. The odd element has been improved from its predecessors, but the vast majority remain the same, and some aspects have actually become worse this time around.

As always with this franchise, you play yourself as a rookie investigator partnered up with the cast of the show to solve five cases. Each case takes you to a different crime scene where you gather evidence, then to the morgue to talk to the coroner about the victim, and finally to the high-tech CSI lab where you process your findings using a selection of forensics machines: a spectrometer that lets you identify different chemicals, a fingerprint database, a microscope and so forth. As well as processing each, often evidence can be compared together; match the fingerprint on the murder weapon to that of a suspect, and a link is established in your case file. When you've made enough discoveries, you can approach the police chief to ask for a warrant, and bring suspects in for questioning or get permission to scour a new location for clues. Finally, you'll find the definitive evidence that links a suspect to the murder and be able to close the case as they own up to the whole story, confronted with your efforts.

In previous games, the last of the five cases has been cleverly linked with the previous four, a sort of meta-case which features key elements of the others. Here, the final episode only has the most tangential of links to something which happened earlier. As such, it's baffling that you can't play these five unrelated scenarios in any order you choose, but each case has to be unlocked in sequence. This wouldn't be a problem if they were all gripping mysteries, but the scenarios here are uniformly dull. Naturally, there is a bit of mystery introduced (the first suspect in the crosshairs, of course, is probably not the villain), but the situations themselves are fairly unimaginative. And although the dialogue and characters are perfectly functional, they simply aren't very interesting. Apparently there are only a few Vegas archetypes to choose from, as just about everyone here is in show business: pole dancers, ex-television hosts, a fire breather, and a prize fighter form the focus of the first four cases.

The fighter case is a little confused. The fighting league involved seems to be modelled on staged tournaments (the combatants wield katanas) but the case hinges around a match-fixing conspiracy. Did any of these people imagine the opponents would cut each other up for real? Would anyone take bets on something so evidently phony? The best of the bunch is that last case, which, if nothing else, does feature some engaging twists involving drag artists and a retired cop. The reveals are a little less predictable, the world feels deeper and the history more interesting. Overall, though, if you are hoping for the cheeky fun of 3 Dimensions’ self-parodying videogame case, you'll be sorely disappointed. If you’re hoping for a handful of forgettable murders (and it is always murders, as no other crimes exist in Las Vegas, it would seem) you are in luck. Expect to visit mostly typical boring locations: interiors of sleazy strip clubs, hotel rooms and so forth. There are one or two curveballs – a ring in the fighting tournament, for example – but by and large the locations are Vegas-as-usual.

I might be ready to forgive the lack of imagination shown in the choice of settings if each were lovingly rendered graphical showcases. Not a chance. In 2006, the first 3D game in the series already looked a bit creaky. But here we are, nearly four years later, and I can honestly assert that the graphics are worse. The characters were always a little unnatural – neither quite realistic nor stylised enough – but here the CSI team are all full members of the Uncanny Valley Residents' Committee, with each model a little more generic, the textures less detailed. There's also some horrible rendering of glass objects, laughable water effects and awkward animation (the cutscenes are particularly poor). It's an unsightly, unimmersive world to play in. Some of this may be down to the fact that the game is also releasing on the Nintendo Wii, but surely a scaled-down version could be released for less able hardware instead of lumping PC/Xbox 360 owners with dated graphics. The credits indicate that that some the graphical duties were outsourced to an animator-for-hire, which might further explain this visual step backwards.

As for the audio side of the presentation, at least this has remained fairly good. Returning players might be bored of hearing largely the same bits of music by now, but they're authentically reminiscent of the series. Also, most of the cast lend their voices to their dead-behind-the-eyes computerised counterparts, and the rest of the voice acting is once again acceptable to good. Being based on the show's ninth season, there's no Grissom or Sara to be found, but Laurence Fishburne pops up from time to time, lending a little of his famous gravitas.