Thank you for helping us help you help us all
This looks like it could end up as a pretty amazing game.
First off, the puzzles were well done.
I do question, however, the repetitive use of keycards. It's like Zelda dungeons: one key per door. Makes no sense. I'd shape it to a different level of keycard, like keycardlvl1access, lvl2access in order to access different colored doors.
Also, you say you're adding timers, so I hope you implement those correctly instead of just putting a timer in there for no reason. The timer in Portal was a countdown to the completion of GLaDOS' fresh batch of neurotoxin.
Also, make sure you insert the correct GLaDOS quotes, because it'll sound weird if she calls you a test subject when you work there.
I think it'd be a cool beginning, (rather than a table, some graffiti, and a big tv)to start in an office with a computer you can play with. And then the doors are locked and your alone in the office, and you use the computer to open the door and begin the game.
I'd also suggest adding interactive useless trinkets. People love those.
If you need help with anything, you can pm me, i've had experience in this sort of thing.