Valve Complete Pack | Steam | £18.99 (75% saving vs RRP)
This is some great value, at least if you don't own the majority of these bona fide classics. You get all the Half-Life games, both Portals, both Left 4 Deads, both Team Fortresses (the second is F2P but still on here for some reason), all the Counter-Strikes including GO, Richochet, Day Of Defeat...
Hang on a second. £18.99? 1+8+9+9 = 27 = 3 x 3 x 3 ... HALF LIFE 3 CONFIRMED! You heard it here first.