ICFP Programming Contest
Solve specific task in three days time, using any language. This is an annual functional programming contest, so it was as much a competition between the languages as it is between the teams. Winners of this contest are true engineers (and possibly great mathematicians). Haven't won anything here yet, but that doesn't stop me from entering ^_^;

International Obfuscated C Coding Contest
Write most obscure C code in limited size. Winners of this are true masters of the C language, although the judges seems way too laid back compared to some other organizers I have seen. My winning entries were saitou.c, rinia.c, akari.c, nyaruko.c, misaka.c, sinon.c, fuuko.c, nuko.c, violet.c, and mile.c.

Transcendental Ruby Imbroglio Contest for rubyKaigi
Obfuscated Ruby contest. I was "Most illusionistic" in 2015, "Most solvable" in 2018, and "Most playable" in 2022.

ACM International Collegiate Programming Contest (World Finals)
Solve maximum number of problems in limited time. Winners of this contest gains the privilege to claim that they are the best in the world. Participants may claim that they are among the best ^_^; Our team placed 27th.

ACM Regional Programming Contest
Solve maximum number of problems in limited time. My team placed second place once ^_^. Top few teams advance to the world contest.

UCSD Programming Contest
Solve maximum number of problems under few hours. Purpose of this contest was mainly to find members to represent UCSD for the ACM programming contest. My team scored first place twice ^_^ These days I no longer participate as a contestant, but help setting up and judging the contest.

Enix Game Contest
Create one game for any platform, no restrictions of any kind were placed. Contest is sponsored by Enix (cash prizes). My entry has long been lost.