Mount & Blade: Warband

For this achievement, you have to win a round of "battle" mode. This mode pits two teams against each other, just like team deathmatch - but unlike team deathmatch, there are no respawns in battle. As soon as everyone on one team is killed, the round ends.

For me, the achievement didn't unlock until I stayed alive in a round my team won. (Thanks to matdan for confirming this)

I found that the best way to stay alive was to play a fairly open map, riding around on a horse. Make sure you avoid people if you can see that they are waiting for you with a spear - that's a quick way to get killed. Try instead to flank people to catch them unaware - you can then scythe them down without much risk. Additionally, try to avoid other horse riders, as battles with them are usually 50/50.

Of course, you could always just try and hide and let your teammates do the dirty work, but beware, this could get you kicked.