Okay, Portal 1 then for seeing through cascaded portals and warped spacial coordinates. I wouldn't say Narbaculare drop because, firstly, I'd never heard of it p), and secondly that's basically a prototype from the same people created as a university project, so it's effectively the same technology from the same people getting the same credit.
3D Realms demoed dynamic portals (Prey) in 1997.