This is an old scenario from long ago, here for your convenience. Made with bits from the orphanage and a dormant map from adam ahswell's hard drive. All you need is a clean copy of the marathon basics, no custom pieces.
updated the terminals to be spelled correctly.
The update to this set may have a few slight differences from the originals, but the textures are so amazing its hard to pick faults.
Finally the sewage set is interesting to look at.