Back when the original xbox was top of the range and I was a rosy-cheeked lad I remember when I finally completed Halo CE and Medal of Honor Frontline. Those games took me probably a year and a half each to complete, so finishing them gave me a level of satisfaction I have probably never felt since.
I was so overjoyed with finishing MOH:F that I replayed the last level every single day for about a month to see the finishing cinematic.
The final level of Halo is a vehicle race on the warthog. The first time I tried it I got nowhere near the end and ran out of time, the second I entered the hangar bay with about 25 seconds to go, ran through the barrels as I got swarmed with flood and covenant, 10ish seconds left I realised I wasn't going to make it to the ship, but I ran on anyway desperate and hopeless, eyes glued to the timer. At around 7 seconds I just reached the long ramp to the ship there was no way I'd reach the Swordfish at the top, but I just ran on anyway, I could do nothing else, I could not give up. I was so close I was determined to keep going to the last second, even if I knew it was too far away. At 3 seconds the game cut to a scene of you reaching the ship, boarding it and escaping, because you didn't have to physically reach the ship to finish the game, just a bit up the ramp for the final cutscene to start.
I was emotionally drained and completely exhausted. It had taken almost two years to do it, but I finished the final level of Halo, with three seconds to spare, in a situation I had lost all hope in, but I did it. I escaped on the fighter, I blew up the ring, I killed the covenant and stopped the Flood. I was victorious.