Infinite Search Space: optimization contests, back after 13 years

For many of us, Al Zimmermann's contests are the gold standard: one beautiful problem, months to chip away at it, a leaderboard that counts every improvement, and results that still turn up in the OEIS. ISS was built in their image. Its founder learned the craft on Al's problems, finishing 10th in Retaining Water. ISS's very first About page thanked Al, and it still does.