Low-key thinking about how a Squid Games joongdok could be an interesting story. Kim Dokja joins the games because, like everyone else, he's in desperate need of money. He's hounded by loan sharks, has no family he can turn to, and is in wretched straits. But when he realizes that this is a death game, he doesn't have much expectation to win. He didn't have friends growing up. He barely played these childhood games and only knew them through passive observation. They weren't difficult, at least, but he doesn't expect to make it far at all.
However, he's smart. And after meeting another man Yoo Joonghyuk, his plans change a bit. Yoo Joonghyuk helps him to cross the finish line in one of the games despite the risk to himself. And after that, Kim Dokja learns a bit about him and how Yoo Joonghyuk is single-handedly taking care of his little sister and needs this money to escape from the basically-slavery job he currently has that's keeping him financially trapped in shady business. But he doesn't like the thought of everyone around him dying to get him that money and fully plans to vote to end the games (even if it doesn't work out).
Kim Dokja decides that he's going to survive and help Yoo Joonghyuk out. He might not be able to save himself (nor does he really want to), but maybe his death can be a noble thing for a guy like Yoo Joonghyuk. So, without telling Yoo Joonghyuk, he fully plans to assist this guy to reach the end no matter what. Up to and including his sacrifice.