"The Thirteenth Floor" should be on this list. Came out around the same time as "The Matrix" and got sort of overshadowed by it, but was better for my money. Gretchen Mol is the daughter of a murdered computer programmer of a virtual reality world, and has to "go into" the virtual reality world to find a clue as to the killer. Also stars Vincent D'Onofrio as a character in the virtual reality world, which is based on 1930's LA (the "real" sequence of events is in present day LA).
Not as much "action" as the Matrix, but it does not spoon feed the viewer. Actually forces the viewer to think. Maybe not a good idea for box office receipts after all.