Why do you want to restrict Black, the side that has a disadvantage at the start already? It's White who should be prohibited from castling at move 4 if you want the Berlin to be banned with no significant damage to either side's winrate.
However, I should stop blaming top level players for entering the endgame early after I exchanged queens at move 11 in one of my best games
(ironically, I did it against the Staunton Gambit, where the endgame usually doesn't come early; stay tuned, I'll post it in BBV anyway when it's finished). Endgames can be colourful sometimes.
Last edited by coon74; 09-18-2015 at 08:58 PM.