There was also an issue with memory limitations, so we changed it to three planets. (shmuplations.com)
Ok, I am no expert, I have no idea about memory limitations, graphics limitations or anything that's involved with creating games. (fingerguns.net)
Memory takes up physical space on a chip, so there will always be memory limitations in computing as we know it today, and no amount of custom silicon can change that. (uphold.com)