Cute game! The 2-8-8 rule only holds up for the first 18 elements, so the configurations are off beyond that, but I assume it would've been a bit more annoying to make it work "correctly"
Yes I am aware of that and actually planned to make the last element acheivable Calcuim (the last to follow the rule), but for some reason I implemented it wrong, making the last one Selenium. In futures versions I will make the electron placement correct. Will be a fun coding challange.
