LaMarcus Lowe scored six points during a 12-2 run as the Titans (18-13, 11-17 Horizon League), who shot 15 of 23 for the half, took a 59-49 lead with 9:32 remaining.
They led the rest of the way, but the Penguins (15-14, 10-8) cut the margin to 72-71 with 1:31 left. After two free throws by Simon and one by Youngstown State’s Ashen Ward, Eli Holman’s dunk with 9 seconds left put the Titans up 76-72.
Ray McCallum added 15 points for Detroit.
Kendrick Perry scored 22 points, 17 in the second half, to pace Youngstown State. Both teams will host first-round games in the conference tournament on Tuesday.
The Penguins’ 10 conference victories, after winning two last season, is the biggest one-season improvement in Horizon League history.