Sin Episodes: Emergence represents an upcoming trend to release cheaper games in episodic form. The reasoning goes that after each episode is out in the wild, the developers can tweak, expand and upgrade the game as players make suggestions and technology changes. To this end, both Sin and Half-Life 2: Episode 1 are available for US$19.95 each via Valve’s online Steam service, promising roughly four to eight hours of gameplay with new instalments released over the coming months. We need to paint this picture completely, because if you’re after an involving game that’ll keep you occupied for weeks, this isn’t it.

Sin Episodes is a sequel of sorts to the 1998 shooter, Sin. Unfortunately for Ritual Entertainment, it also hit at the same time as the original Half-Life, which deservedly got all the attention. Sin’s now been resurrected based on the Half-Life 2 engine, and it shows -- for visuals alone, it’s hard to beat. It’s sad, then, that the innovation stops there: it’s a standard run-and-gun shooter with little in the way of puzzle solving; the weapons are simple; and the derivative, genre-based sci-fi plot won’t keep you glued to the keyboard.

But while the elements shouldn’t work on paper, the end result is one of the more enjoyable first-person shooters we’ve played. It’s fast, fun and doesn’t take itself too seriously. The world is immersive, filled with realistic locations and all the wonderful physics that the Half-Life 2 engine offers. The three weapons are simple, but each one has its own strengths that are useful throughout the game. And finally, although we’ve seen the story before, it’s well-paced and cracks on relentlessly until the end.

It’s hard to criticise a game that still has a couple more episodes left, but taken as a standalone title, it’s a fun romp that’ll keep you going for a weekend. Ritual says there are tons of goodies and enhancements coming up in the next episodes, and we’ll be watching how the series develops. We’d recommend waiting until you know where it’s headed before you jump on board.