Instead of going to Oregon to stake a claim on America's future, you decide the fate of a group of survivors looking for a safe place to live in a post-apocalyptic world overridden by zombies. You travel from Washington DC, that's about to be nuked, all the way to a safe haven in, you guessed it, Oregon. The game is faithful in every way it can be to the Oregon Trail, except where it could be made more thematically appropriate to a zombie apocalypse, with multiple additions to improve the simulation and theming. Seriously, name a feature from Oregon Trail and it's there. Dysentary? Check. Bad water? Check. Tombstones? Check. You get the picture.
Oregon Trail's 'hunting' minigame, being the best part of the original, has become a bit more central to the experience with Scavenging and Jobs using it, with a few others including Defense, Surrounded and Bandit Raid events using the same shooting mechanics.
When Scavenging, you no longer shoot a 2000 pound buffalo to carry back 100 pounds of meat. Instead you rummage around a wilderness, collecting any supplies that pop up (including food, cash and scrap that you can use to repair your car), while avoiding and shooting zombies that swarm in on you. Learning to control the flow of these zombies to reduce the amount of ammo I have to spend was a fun mechanic to master (no doubt aided by my recent experience with Gauntlet), and I must say, is probably the best way to ensure your victory at the game.
In a funny way, Organ Trail is one of the most complete zombie apocalypse simulations I've played, and if you like the genre, you really should play it just because it's a fun game. If that's not enough to attract you, maybe the novelty of recreating the Oregon Trail experience on a modern platform with a modern genre is enough. I would happily recommend Organ Trail even at the premium price of five bucks.