When Microsoft asks you to go and see Halo, you go. No matter what it actually is, and especially when it's something as hush-hush - well, at the time - as Spartan Assault. Having arrived at a swanky London office, the Microsoft rep was on the phone to a journo who had forgotten to attend. There was a vague sense of what feels like panic on the other end, a hastily rearranged interview/hands-on time, and the feeling that someone over there just got Malcolm Tucker'd.

They call, you go. Because people love Halo.

The question is, however, whether they'll love this one.

Full-fat, first-person, four-player split-screen Halo this isn't. Instead, it's a Windows 8 platform-only deal - a title that can be played across your PC, tablet and phone - which has got its roots in old-school, top-down shooters like Smash TV, Total Carnage, and crusty old Robotron 2084.

Not that Spartan Assault is going to look anything like those games - 343 is promising that this will resemble Halo in every way bar the viewpoint. Massive vistas, imposing war machines - and their munitions - flying past at breakneck speeds, and a tidal wave of neon communicate the Halo vibe well.

The hands-on demo consisted of three missions. The first was a classic run-and-gun affair, with Commander Sarah Palmer assisting fellow UNSC troops as they're about to be overrun by suicidal midgets and Elites. 343's executive producer of publishing Dan Ayoub made a big deal about the twin stick controls before we started - they 'move' with you, as your hands inevitably slide around the tablet/phone you're playing on - and it worked well. The mission was to beat them back, engaging in pitched battles over multiple 'screens'. Dual-wielding, grenade throwing, shot-gunning, grunt-slaying: it's all there, just, well, different.

The second mission had more in common with tower defence than anything else. Two machine gun turrets lie outside of two doors, which must be protected at all costs from marauding suicide bombers. Every now and then Brutes and other units will spawn in to keep you on your toes, but it's pretty basic fare: fire turrets until they overheat, hop off and deliver hand-held gunishment, try not to let anything through.

The third and final mission enabled me to jump into one of Halo's signature vehicles (the Wraith) and wreak havoc on enemy forces: smashing my way through their assorted lines until - inevitably - I had to jump out and start sabotaging enemy ordinance.

Halo spartan assault

Having played through these three missions, the first feeling I had was that of being underwhelmed by the experience. There's nothing really wrong with it - and I quite enjoyed destroying Covenant forces with the sort of impunity usually reserved for Arnie or the President. But at the same time I couldn't help but feel that it would only ever be seen as a stopgap. A little brother to the main series, meant to be played primarily on platforms not up to the task of doing a full-on Halo game, whether that's down to input restriction or something else.

Smash TV, Robotron and the like might be influences, but those games were also focused on either frantic bids for survival, score-hunting, or both, depending on your skill level. Halo: Spartan Assault has a slight score attack vibe, with medals and challenges to be earned and unlocked, but at the same time there was no urgency to it. I asked Ayoub whether this was a fundamental problem: Halo is a franchise known to take itself 'Very Seriously Indeed'. How do you make that work with a game whose influences include Total Carnage, a title where a sample line of dialogue is 'his ass is grass and I'm the lawnmower'?

"We talked before about building it specifically for these kind of devices, and what that forced us to do was look at some of the conventions and what we would normally want and expect in a Halo, and tailor some things that worked more appropriately on these kind of devices. When we had to make those kind of decisions we opted for form factor and what mobile conventions are and what players expect as much as possible."

Which doesn't really explain too much, it must be said.

In fairness to 343, it has attempted to keep the feel of the series intact. As mentioned, there's always plenty going on (I played on a Surface tablet - on phones geometry and effects will be scaled back, but it still looks good) with tracer fire, artillery and war machines flying overhead. There will also be full CGI cinematics, as Commander Sarah Palmer and Spartan Davis undertake their first missions and relive classic battles via a tactical simulator aboard the UNSC Infinity. Small 'snippets' of CGI cutscene will also move the story along, which is set between Halo 3 and 4.

There's also a level of persistence on show that should delight fans of the series. 343 hopes weekly challenges (including mission-specific ones) will keep fans playing, as well as tracking stats and leaderboards. You'll also be able to unlock Achievements, XP and emblems in Halo 4.

Halo spartan assault

Despite all of these inclusions - and all of 343's undoubted hard work - it's difficult to see Spartan Assault capturing the series' trademark sense of wonder. Seeing these sights through the Chief's eyes is very different than seeing it from above, and Spartan Assault proves it. There's also the nagging feeling that the game is caught between two stools: the over-the-top, combo-timed, death-dodging silliness of Smash TV or a Geometry Wars, and the need to cram in everything else that makes Halo so popular. It doesn't feel compulsive enough to drop in and out, and yet the levels - or at least the ones that I played - didn't seem long enough for other uses either.

Ayoub told me that Halo has always driven the platforms that it has appeared on, and that 343 wanted Spartan Assault to do the same on Windows 8 devices. While it's impressive that you can play the game across the Windows 8 'ecosystem', the question remains as to whether this Halo game will drive players to the platform. We'll find out when it launches next month.