Procure pelos JAM's que existem por aí, como JAM, Code JAM, etc.

Esses aqui são da área de jogos
https://globalgamejam.org/
https://v3.globalgamejam.org/2022/jam-sites/global-game-jam-curitiba-2022-pucpr
https://ludumdare.com/
https://nordicgamejam.com/

Programação
Topcoder: https://www.topcoder.com/
Codeforces: https://codeforces.com/
Atcoder: https://atcoder.jp/
CodeChef
Ensina mais há competições também
https://www.codechef.com/

$LeetCode: https://leetcode.com/
Google: https://codingcompetitionsonair.withgoogle.com/
ICPC (International Collegiate Programming Contest): https://icpc.global/

A palavra-chave Hackathon pode ajudar também.

Hacker
$HackerRank: https://www.hackerrank.com/
Hacker Cup: https://www.facebook.com/codingcompetitions/hacker-cup