Hamler joins the Colts after three years with the Denver Broncos.
O'Hara, who plays both tight end and defensive end in high school, will likely play tight end for the Nittany Lions.
While he wasn't a Nittany Lion in Penn State's 2021 loss to Iowa, Robinson was set on revenge.
Hayes is the second running back to commit to the Nittany Lions' recruiting Class of 2025.
Drew Allar threw for 166 yards and four touchdowns Saturday at the White Out despite a lack of explosive play.
"It was raining and it was still filling up to the brim in the stadium. Their energy is infectious. And I love them and I appreciate all they do for us."