Half-Life 2
When battling the hunter-chopper in Water Hazard, it’s not worth getting out of the boat; stay inside and simply run over power-up crates (most of them will give you suit energy). All you need to take the bastard down is your mounted machine gun and patience. The chopper’s pretty vulnerable after dropping a wave of bombs, but take advantage of the terrain, too – you can lead him from one end of the level to the other, and the lower he dips to the ground, the better.

Half-Life 2: Episode One
Having trouble getting through the Citadel’s energy conduits? You’ve got two options: Bring a shield (the panel you pried off will do nicely) or get ready to do your best Mario impersonation and jump over the energy balls, platform style.

Half-Life 2: Episode Two
Killing antlion grubs gives you health, but they also give you an achievement – if you can kill 333 of them! Be diligent in your search; sometimes you’ll find them tucked away in pits, nested overhead, or even inside cabinets. Open everything, and if in doubt, blow it up. The crowbar and gravity gun’s main attack should take care of most of them, but same some 9mm shots for the hard-to-reach grubs. And against those acidic antlion workers, your best bet isn’t a shotgun – it’s a rock hurled with the grav gun. One-shot squish!

Portal
You’re armed only with the portal gun…but are you? One deceptively easy way to clear level 14 – the first appearance of turrets – is to use a cube as a shield and deactivate the turrets by simply running into them. If you want to get fancy, you can always throw a portal on the ceiling, then drop the box from above, but it’s often quicker to just bump and run.

Team Fortress 2
The Pyro guy, one of the three Offense classes, will get ripped to shreds in a frontal assault. Better to play him as an offense-defense hybrid; he’s most effective when ambushing enemies from around corners. Show your face to lure an enemy over, then hide behind a wall and toast the bastard. Your flamethrower doesn’t kill outright so be ready to circle strafe, or better still, work with another teammate as a two-man strike force.