According to Stockfish, chess would be more equal without castling. (+0.4 w/castling enabled, +0.1 w/o castling) : r/chess

Castling, Smallfish Chess Wiki

Is castling in chess possible when the king is in check and there are no moves left without castling? - Quora

Frontiers Learning to Play the Chess Variant Crazyhouse Above World Champion Level With Deep Neural Networks and Human Data

stockfish - How many moves out do the static board evaluations use? - Chess Stack Exchange

Info] How to compile the actual 64Bit version of stockfish chess engine - Off-topic - Armbian Community Forums

PDF) Learning to Play the Chess Variant Crazyhouse Above World Champion Level With Deep Neural Networks and Human Data

First-move advantage in chess - Wikipedia

First-move advantage in chess - Wikipedia

Fischer Random 2: Wesley So tries to castle illegally