GE Tigers started out as unquestionably the top team in Korea in their first season in the LCK, in first place with a 7-0 match record and a 14-2 game record at the end of week 6 of the spring season. This placement earned them an invitation to the IEM Season IX World Championship in March. However, after defeating Cloud 9 and SK Gaming to win their group, they lost in the semifinals 2-1 to Team WE - who entered the competition as the 12th-place team in the LPL. This led many casters and analysts to label it the biggest upset to date in the entire history of competitive League of Legends. After their return to Korea, the GE Tigers's record worsened, and they dropped sets to both KT Rolster and to SK Telecom T1. They still finished first in the round robin with a 12-2 record, but in the Playoffs they lost to SKT and missed out on the Mid-Season Invitational. Prior to the start of the SBENU Champions Summer 2015, the GE Tigers were sponsored by streaming company KOOtv and changed their name to the KOO Tigers. KOO ended the regular season of Champions Summer in 4th place.They beat NaJin e-mFire 2-1 and CJ Entus 3-0 to advance to the semifinals where they played a close series with KT Rolster but lost 3-2, ultimately ending in third place. Because SKT won the finals, KOO automatically qualified for the 2015 Season World Championship as the second seed from Korea with the most circuit points. KOO was placed into a group with Counter Logic Gaming, Flash Wolves, and paiN Gaming. They placed second, ending with a 4-2 record with both losses to Flash Wolves. They beat KT Rolster 3-1 and Fnatic 3-0 to make it to the finals against SKT. However, they finally fell in the finals with a 3-1 loss.
After Worlds, Tigers dropped their title sponsor from their team name, and they played in the KeSPA Cup as Tigers. The Tigers played in the KeSPA Cup but they were upset in the first round 2-0 by SBENU Sonicboom. On January 5th they renamed to the ROX Tigers.
During the 2016 LCK Spring Split, the ROX Tigers dominated domestically in similar fashion to 2015. They finished the regular season with a 16-2 match record, losing only to KT Rolster and Samsung Galaxy. Earning first place in the regular season gave them a bye to the finals of the Spring Playoffs, where they faced SK Telecom T1. ROX entered as the favorites this time, but still lost 3-1, earning themselves second place for the spring split.
January 5th, Tigers renames to ROX Tigers and Peanut joins.