One of the best games ever made. Dauntingly complex, but mindblowingly considered and exceedingly well executed. It’s hard to overstate the brilliance of Dota 2, a game beyond compare.

The one that changed the game. The impact of Half-Life is immeasurable, but I’ll always look back and be thankful for that intro train sequence, knowing that all the new games I like learned from it.

An instant classic that dared to expand the lore of its predecessor to intriguing depths and flex how physics can be fun in videogames. Virtually flawless game design.

Very creative and fun, Episode is varied and a great example of Valve being in the zone. A great albeit tantalising “conclusion” evidently leaving the world wanting more. Google and read “Epistle 3”!

An OG LAN party co-op shooter, whose influence cannot be understated. Incredibly fun if you can get a stack together, especially IRL.

More of the same but better. Tremendous fun with friends, especially if you can get in the same room. Valve struck on something simply fun and perfected it here.

Short and sweet, Portal has a simple concept which lends itself to all levels of complex puzzles. Nowadays it lives in the shadow of it’s unbelievably good sequel, but the concepts started here.

A perfect sequel expanding massively on an already brilliant puzzle mechanic. The puzzles are challenging and well designed, but the centrepiece is the plot and specifically the characters.