Can i be an SCP?
Warg left it open in the OP, though it's important to point out that 'playing' an SCP should be a difficult and extremely antagonistic role. Especially for humanoids, the general rule of thumb is basically:
1) Make the SCP miserable and/or dangerous to be around.
2) Would you ever, under any circumstances imaginable, want to be that SCP in real life? If so, GOTO 1.
You'll spend all your time locked away in a box/cell/containment unit, except when white-coated scientists are doing horrible things to you/making you do horrible things to other people, in order to figure out how you work/what you do. Trying to escape means taking on an organization that makes the MIB look like your grandma's knitting circle, and they've probably written a book specifically explaining how to stop/capture/kill you. You're playing "against" all the other PCs, and all the NPCs, you (probably) have superpowers of some kind, and you're the underdog by a ridiculous margin.
TLDR: Warg says yes, and Warg is in charge. But if you're not already deeply familiar with the SCP universe/site, I would advise against it, because it looks like Warg is planning to play the 'verse fairly straight, so being a sentient humanoid Scip is going to suck giant hairy monkey balls pretty much 24/7.