Portal

Released alongside Half-Life 2, Portal is part of Nvidia's push to give its Shield handheld a bit of credibility with seasoned gamers.

This critically lauded and commercially successful first-person action-puzzle title is famous for its ingenious puzzles, humorous dialogue, and cake song.

The good news is that all of the things which made the original so essential remain intact here, but it's not a totally successful conversion.

The premise of Portal is incredibly original. You assume the role of a test subject within the Aperture Science Enrichment Center who is tasked with completing a series of challenges involving the now-iconic Portal gun - a device which can open portals allowing the player to move instantly from one location to the next.

Using this gun - and adapting tactics to increase your momentum as you pass through each portal - you must solve each increasingly difficult room.

Your guide through this rather unnerving environment is GLaDOS - otherwise known as Genetic Lifeform and Disk Operating System - a computer AI which dishes out encouragement and lies in almost equal measure.

The dialogue delivered by GLaDOS ranks as some of the best ever featured in any video game, and a massive amount of Portal's appeal is finding out what this amiable but sinister computer is going to say next.

Portal's puzzles are also fantastic, making brilliant use of the game's central portal-jumping mechanic and causing more than a few furrowed brows along the way.

The controls have been superbly tailored for the Nvidia Shield, with all on-screen prompts referring directly to the console's physical buttons and sticks. In that regard, this isn't some quick and easy mobile port.

However, elsewhere the conversion is less assured. The stark visuals seen in the original title are reproduced well enough, but some of the detail has been sacrificed in order to keep the pace at an agreeable level.

Like its stablemate Half-Life 2, Portal suffers from a framerate which dips and jumps all over the place, although it should be pointed out that the effect isn't as jarring due the lack of complexity in Portal's contained stages.

Both Half-Life 2 and Portal are - at the time of writing - being sold for £5.99, and while you could argue that the former offers enough gameplay to justify that cost, the latter is a much shorter experience and really should have been sold for less.

If you've already played Portal then there's little point in paying additional cash for what is a slightly weaker port, but if you're one of the very few that missed it the first time - and you happen to own a Shield - then it's well worth a look.

It's a real gem of modern game development and everyone should play it once - just don't expect a title which lasts more than a few days.