I've talked about this on another thread, but Ecco the dolphin is based on the scientific experiments conducted by neuroscientist John C. Lilly, in wich he and his main assistant Margaret Howe Lovatt, and with funds by NASA, tried to prove the cognitive capacities of dolphins by teaching them human speech. Lilly however started experimenting with LSD while on a sensory deprivation chamber, and started to hallucinate that he was being contacted by a intergalactic alien counsil called ECCO, and became convinced that breaking the language barrier between dolphins was the key to a new era of intergalactic peace. The experiments were called off when progress with the main dolphin Peter stagnated, mostly due to him reachin sexual maturity and, infamously, becoming sexually interested in Margaret, who... erm... "gave him a hand" to help him focus multiple times. The experiments were called off, but the many books Lilly published during and after them were what gave the dolphin that pseudo mystic and wise characterstic that are so prevalent in pop culture, and what inspired the ECCO the dolphin series, plus the lab where the experiments took place appears in the first level and intro of the game in the background. Peter the real dolphin died, apparently by suicide when he was separated from the caretakers he knew all his life...
Ok since ECCO is not really that obscure and to make up for me mentioning this piece of trivia before, another one: Primal Rage originally had a final boss named Necrosan, but was cut out due to time limitations, but his background is still used for the boss rush that took his place as a last battle. He was supposed to make his debut in the canceled sequel