Serious Sam/Awesome

The First Encounter

 * The final boss fight with Ugh-Zan III. Epic doesn't even begin to describe it. Crowning Music of Awesome doesn't hurt at all.

The Second Encounter

 * The entire "Grand Cathedral" level.

Serious Sam 3

 * Sam says "Just encountered a warship. Scared it off though". Sam was on foot when fighting the warship.
 * "It's not over until I teabag every last one of you alien motherfuckers."
 * "The Guardian of Time". Forget everything you know about The War Sequence; this leaves every one in the series in the dust.
 * This one deserves a bit of explanation. After powering up the Time Lock and thinking that his work is finally done, things take a turn for the worse for Sam when he finds out that a final, MASSIVE assault has been launched by Mental, that the rest of mankind is being systematically wiped out, erasing any possible hope for survival they had up to that point (The last-to-final level is ominously named "The Last Man on Earth"), and that Mental himself is coming to oversee the final destruction of Earth. After having both his Voice With an Internet Connection and Love Interest killed in the assault, Sam makes a final push towards the Time-Lock through a canyon under stormy, almost alien skies, fighting waves upon waves of every single kind of enemy in the entire game, culminating with a stand against massive WAVE after WAVE of Kleers and Khnums, and AFTER that, a battle against the final boss, Ugh-Zan IV, while still being rushed by hundreds of Khnums, Major Biomechanoids, and attack helicopters, and a final dash to the Time Lock as Mental finally arrives and hurls the bloody MOON towards the Earth, completely destroying it right after you manage to jump through the portal. All of that while epic music blasts on the background, and the ample supplies of ammo guarantee you with almost unlimited ammunition for the fight. And you'll need every single bullet.
 * How many enemies does Sam kill just in that one level? Over seventeen hundred, followed by a three hundred foot tall boss and endless waves of respawning attack helicopters, Khnums, and Major Biomechanoids.
 * The DRM, which spawns an immortal scorpion who will hunt players who pirated the game down. No "Always Online", no Secu-ROM, no Starforce, no bullshit like that. This is what DRM for any game should be like.