Is it still possible to develop new openings? I have been using this opening that I accidentally started using a lot and then got good results in Blitz games. I'm almost sure it won't last a chance in standard games but it made me curious about a bigger question:

If I can't find an opening variation (and it really is an opening, say it starts after 3-4 moves from the beginning of the game, not after 20!) in databases, does it mean that it hasn't been good enough to become famous? In other words, is the age of opening theory over with all the stronger ones already being developed and analysed?
Yes, it is still possible to find new openings. The combinatorial space after 3-4 moves is such large, that there are still many uncharted waters in opening theory.

Many of such openings probably violate learned principles and are pruned by experienced players before going deeper into the game tree, but there may be undiscovered gems among them.