A familiar plot – meddling with forces beyond our control – and some new weapons greet you as you once again enter the Mars UAC facility.

There are few boys, and likely some girls, too, that aren’t attracted to the idea of building a castle.

Gone are the innovations introduced in the first game – allowing the player to upgrade specific unit traits via the unit itself; the exciting feel of progressing from one epoch to another and general playability.

The control is simple.

The emphasis is placed on careful investigation of each environment and the wise selection of appropriate weapons and tools.

The world is Paragon City, in which costumed heroes patrol the skies or walk the streets.

It isn't an add-on, a mod or a new way of playing the world's most popular online shooter. Counter-Strike: Source is the same game that's known, loved and often responsible for gamers sitting motionless for days on end. But it's now been ported to Valve's new 3D engine, the Source engine, giving us our first glimpse of the technology that will be powering Half-Life 2.

For a company whose only other major release was the original Half Life, Valve has pushed the boundaries with fresh, bold gameplay that stays true to the legendary legacy.