I was looking for like 2 days times through W. D Gaster's wiki, and some google images where i found a photo with sans basements... And there was a blanket in the corner where it said that there is an invention and it's broken. Remember Gaster's followers right? Well all of them told us about that Gaster was the first royal scientist, and he died cause an invention. Now let's go back to sans basement, where i said about the broken invention , but before that remember the Gaster Blasters that sans uses them in fight? Maybe thats the invention that killed Gaster, like the prototype of the blaster killed him. So the broken invention might be the blaster, and sans basement might be Gaster's lab before becoming a royal scientist. So Sans repaired the blasters and used them. I saw some other theories that Gaster might be Sans and Papyrus's father, It's false, but keep hoping it can be true. Still maybe when he became royal scientist, he wanted to test his projects in his first lab, where that is sans basement. I think this theory can solve the mistery once and for all, so what do you think?