Choosing a System
There are two systems that instantly sprung to mind when I decided I wanted to write a one-shot based on this movie. Cthulhu by Gaslight and Dread. Both of these systems are exclusively horror games, which in their own ways do a great job of portraying the horror genre. Call of Cthulhu uses a sanity mechanic to measure the character's reactions to witnessing horrible sights. The by Gaslight expansion also covers the era that this game would take place the 1890s. Dread on the other hand is a largely narrative game that uses a unique mechanic of a Jenga Tower to resolve action. Anyone who has played the game Jenga will tell you how intense it can sometimes get, when you are playing for keeps. As the game progresses the stakes get higher and the more likely one of the players will die off, just like in your typical horror movie. I think both games are valid choices for this one-shot, so I don't think I will be choosing any particular one at this point in time.
The game will have the players taking the roles of members of a railway construction crew. At the Tsavo River crossing in Kenya. They have been tasked with building a bridge across the river as part of the Uganda-Mombasa railway being built by the British Empire. Roles would include the Chief Engineer, the head of the camp's Infirmary, a Missionary, a head of Railroad Security and various Hindi/native labourers. Shortly after arriving one of the labourers is found dead after being dragged from his tent in the middle of the night. The characters of course don't witness this. They just find the remains of the worker outside of the camp the next day. To set them on the wrong path, I would make the worker that was killed either a foreman or a labourer that had been working for the railroad for some time. Creating a red herring that maybe the death was the result of foul-play. A murder made to look like a mauling by a wild animal, so another labourer could steal the wealthy labourer's earnings. This is what Lieutenant Colonel John Henry Patterson the man who actually shot and killed the Tsavo Man-eaters thought when the initial attacks started. For extra measure to make the players take the bait, I would have the deadman's earnings disappear from his personal effects (the culprit one of his opportunistic co-workers).
More attacks would soon follow (shortly after the characters concluded their investigation into the matter of the stolen money). Perhaps with one or more of the characters being among the next victims. This might be the first time that the characters see one of the lions. It would be up to the players to figure out a way to deal with this (at the moment) pest. Normal methods of hunting will result in failure, (using a donkey as bait for example, these lions prefer human flesh) if the characters camp the spot of a recent attack, the lions move onto somewhere new. Sometimes days, even weeks will pass without there being an attack.
Absence of a threat won't be enough to quell the worker's fear though. In real life Patterson's workers all but threatened to kill him on account of the attacks not happening until he showed up at the Tsavo Crossing. Dealing with worker revolt and desertion will also be a danger unto itself. It might even be appropriate to have a group of workers kill one of the players, in hopes of appeasing what they perceive as Demons in the form of lions. One of the stories I've heard is that some of the workers at Tsavo actually believed the lions were really the spirits of two tribal shamans, intent on driving the white man out of Africa. It's an aspect of the story that I would really love to play up. As this is a horror game, it might even be true. The Lion's really could be evil spirits, such a plot wouldn't be out of place in a Call of Cthulhu game. There was certainly enough things that happened, to fuel these rumours. At one point Patterson constructed a railcar that he used to trap one of the lions. In the car was ten Indian Sepoys with rifles, standing behind steel bars to separate themselves from the animal. They apparently fired at the lion at point-blank range for a rifle. Unable to hit it as the lion was roaring and trying to attack them through the bars, the noise from their rifles disoriented them. The car filled with smoke because the guns they used didn't use smokeless gunpowder. One of the Sepoys ended up going deaf from all the noise. Eventually one of the bullets hit the gate on the other end of the car and made it possible for the lion to escape. After such an incident it would be hard not to believe that the animals were ghosts.