Hidden away in the far north of Fallout 3′s game-world, the area called Oasis is quite a contrast to the rest of the dry Capital Wasteland with its scraggly trees. Here, the mutant tree-hybrid Harold has extended his roots into the ground, and spread his life-giving spores. The trees in and around Oasis are green, healthy and abundant. Oasis is a distinctly different space than the rest of the dessicated landscape
Oasis is also the focus of a moral choice the player must make. Harold wants to end his wretched state and die. His worshippers, the Treeminders, are split: one faction wants to extend Harold’s influence beyond the shelter of Oasis, the other wants to keep Harold alive but limit his growth. The player is given the opportunity to help one of these parties, but also has the option to attack and burn Harold if they’re feeling particularly malevolent. If the player does choose to aid one of the parties involved, the consequences are clear. If Harold’s influence is extended, the green trees of Oasis will likely spread across the Wasteland, bringing it back to life, but this will reveal the existence of Oasis, and expose it to the predations of the Wasteland’s inhabitants. If Harold’s influence restricted, Oasis will remain hidden and safe. But if either of these options is chosen, Harold will remain alive, and endure further pain. If Harold is killed, Oasis’ greenery will end, but so will his suffering.
There is no option which will satisfy all parties. Each option is presented in such a way as to emphasise who will benefit and who will suffer as a consequence of each option. So the player must make the choice based on their own inclinations. The choice comes down to the player’s own judgement of whose need is greater, who deserves most to benefit.
This imbues the player’s experience of Oasis as a space with associations of philosophical and moral choice. This atmosphere is heightened by the religious behaviour of the Treeminders, but also by the green surroundings that convey a sense of being apart from the wider world. Because the player enters Oasis as a functionally separate game-world zone once they pass through the door at its entrance, the underlying mechanics of the game reinforce this separation. That the world outside Oasis lacks greenery and is dry and dead means this separation links morality and growth, as represented by the plants found only there.
What this means is that the ‘spatial rhetoric’ of Oasis presents an argument that the option to stimulate Harold’s growth and expand this area into the wider world is the most moral choice. This is despite the lack of impact on the player’s karma points for any option other than burning Harold. In addition, linking morality and growth, by extension, links morality to pure water, a connection which is reinforced elsewhere in the game world, and has ramifications for the player’s choices as part of the game’s main quest. In a sense, Oasis serves as an argument by analogy for how the player should make the larger choices Fallout 3 presents.