Erik “ztr” Gustafsson started playing Counter-Strike in 2018. At the beginning of his professional career, he played for various mix teams, with one of which he became the champion of GANK-Zone 2018. Throughout 2019, the player also switched between several lesser-known teams, and together with nerdRage, he managed to win a silver medal at ESEA Season 30: Main Division - Europe.
In August 2019, the player signed a contract, where he became the champion of the Nordic Esports League Season 1 - Division 1. After that, he moved to Grillska Eskilstuna and won the title at Gymnasieligan 2019 Fall, then placed in the TOP-4 at Svenska Elitserien 2019 Fall with Valorix Esport.
After this, Erik played for several teams. Between November 2019 and January 2021, he switched teams more than five times. The most notable of them were KPI Gaming and Prima eSport. With these teams, he managed to win championships in tournaments such as King of Nordic - Season 15: Week #5 Swedish Qualifier, OMEN CS:GO Open - Sweden Qualifier #2, and also finished 1st-2nd at Leo Vegas CS:GO Open - Sweden Qualifier #4.
In January 2021, the esports player was invited to join Young Ninjas. After signing the contract, he managed to win the championship at WePlay Academy League Season 6, and also won silver medals at Flashpoint Season 3, WePlay Academy League Season 1: Online Stage, WePlay Academy League Season 1, Ace X Stockholm Open 2021, and Svenska Elitserien Fall 2022. Additionally, he placed 1st-2nd at WePlay Academy League Season 2: Online Stage, and 1st-2nd in the IESF World Championship 2021: West Europe with the Swedish national team.
In January 2023, Gustafsson left Young Ninjas and joined GODSENT. With his new team, he earned bronze at Thunderpick Bitcoin Series #2 and ESL Challenger Katowice 2023: European Qualifier, finished 1st-2nd at Intel Extreme Masters Dallas 2023: European Open Qualifier #2, and became the champion of Subway Suberior League Season 2: Open Qualifier #5 and Tele2 Gaming: Road to DreamHack 2023.
In December 2023, the esports player joined Metizport and helped the team win gold at Subway Suberior League Season 3: Open Qualifier #2, Pelaajat.com Series Spring 2024: Nordic Open Qualifier #1, RES Western European Masters: Spring 2024, and Esportal LuckyCasino Cup 2024. He also finished 1st-2nd in Intel Extreme Masters Dallas 2024: European Open Qualifier #1.
Since July 2024, he has been playing for GamerLegion. With the team, Erik “ztr” Gustafsson managed to become the champion of CCT Season 2 European Series #13, win silver at CCT Season 2 European Series #10, 11, and 12, and place 1st-4th at ESL Challenger at DreamHack Atlanta 2024: European Open Qualifier and Intel Extreme Masters Dallas 2025: European Qualifier.