There are several apps available that let you take part in game-testing gigs and earn money.  Here are some popular options:
HQ Trivia: Join live trivia games and compete against others for cash prizes.
Swagbucks: Earn points by playing games like trivia and word puzzles, which can be redeemed for cash or gift cards.
Skillz: Engage in skill-based mobile games and compete against other players for real money in tournaments.
Mistplay: Get rewarded with points for trying out new games and reaching milestones.
Long Game Savings: Combine gaming with saving money, earn coins by playing games, and reach savings goals for chances to win cash prizes.
Lucky Day: Play virtual scratch-off tickets, lotto, and raffle games daily to win cash prizes, gift cards, and tokens.
InboxDollars: Earn rewards by playing games, taking surveys, and completing other online activities.
Boodle: Play games and take part in daily draws to win cash.