I got to the lever but I don't know what to do next
Hmm. I hope I didn't leave a state where the final cutscene doesn't trigger. I rushed the game out because the game jam deadline was approaching. Once you have at least one guy reach the lever, there should be a cutscene where the president and adjutant discuss whether to pull the lever or not, and whatever decision you make should result in a couple more lines of dialogue and then a game over screen. But switching between scenes at the end was finnicky.