One thing that I still really appreciate about UT was the story's explicit understanding and integration of player control. Something SO:TL and UT share is that they both make commentary on your actions as a player, and how you are complicit in the violence depicted. However, SO:TL takes a sort of... easy road. You have no other choice except not play the game. And given that it costs real world money? That's just a copout, I'm sorry.

In SO:TL, you have no option but to do terrible things. Your options are either do it, or fail to progress. How can your decisions be bad if you aren't making them? It ultimately turns you into a spectator while commenting on you as if you were an actor.

Meanwhile, UT acknowledges you have power. It says "I know you can reset. You can try as many times as you like to do this." and every interaction in the story is cognizant of this.

Did you kill Toriel? Well, maybe you haven't noticed yet, it's been pretty easy so far... Did you kill Papyrus? Maybe... you weren't paying attention. But the deeper in, the more it questions you, grills you, and tries to point towards your power. Sans, at the end, finally calls you out, explicitly pointing to how much power you have. Are you sure you WANT this? Do you CHOOSE this?

In SO:TL, you are tasked with bombing targets on a screen with white phospherous, knowing full well it's horrendous, but not knowing that who you're targeting are civilians. But you can't just... run away and try not to do it. There are no other story paths, you either stop the experience, or continue. I cannot stress enough that this removes any sense of culpability from the experience. You are just along for the ride.