Gaddis (1-1), the junior right-hander, was superb, as he allowed just four hits and struck out a season-high 10 in eight scoreless innings.
Of the four hits he allowed, only Luke Drumheller's eighth-inning single to center was a solid hit to the outfield. The first three singles he allowed, which all came in the first two innings, were an infield single to third, a single when the runner at first was hit by the batted ball, and bad-hop single past the third baseman.
Brandon, the freshman right-hander, pitched a scoreless ninth for his first save. After he struck out the first batter, he allowed a single to left, but then he started a 1-6-3 double play to end the game.
The Panthers (6-12, 1-0 Sun Belt) opened the scoring in the third inning as Daino Deas led off with a single, stole second, moved to third on a bunt and then scored on Jake Corso's groundout, his team-leading 16th RBI of the season.
Gaddis earned his 14th career victory, moving into sole possession of 10th place in GSU history. His 10 strikeouts give him 199 for his career as he climbed from seventh to fourth on the Panthers career chart.
"Hunter Gaddis was amazing," head coach Greg Frady said. "He had all his pitches working and he was basically incredible. I'm proud of how he handled the game today.
"I'm so happy for him to get his first win of the season, because he pitched well enough to win four of his five starts.
"I also want to say that Joseph Brandon did a great job closing it out," Frady said. "We played well in all three phases today. We got some timely hits, we played good defense, and the pitching was great."
App State (6-10, 0-1 Sun Belt) starter Will Sprinkle (1-3) pitched seven innings and allowed two runs on seven hits.
Game 2 of the series is Saturday at 1 p.m.