Head-to-head Doomsday Battles against real players. Same date, fastest correct answer wins — and your rating is on the line.
Free with Google. Unlocks after 25 rounds of the main game.
You and your opponent are shown the same date. No luck, no different questions — pure skill.
Correct beats wrong. Correct-and-faster beats correct-and-slower. Every millisecond of your mental math counts.
Win rating from stronger opponents, defend it against weaker ones, and climb from Bronze toward the Doomsday tier.
Everyone starts at a 1500 rating. Where you go from there is up to you.
You and your opponent get exactly the same date. Each of you answers which day of the week it falls on, as fast as you can. A correct answer beats a wrong one; if you both get it right, the faster answer wins.
Battles are asynchronous. If nobody is waiting, you answer your date now and the Battle resolves when an opponent picks it up — you’ll see the result next time you visit, along with any rating change.
Ratings use a Glicko-style system seeded at 1500. Your first 5 Battles are placements; after that your rating is established and you appear on the Arena leaderboard. Beating stronger players moves you further, and close matches move you less.
Bronze (1300+), Silver (1500+), Gold (1700+), Platinum (1900+), Diamond (2100+), Master (2300+), Doomsday (2500+). Reaching Gold earns the Gold Standard achievement.
Create a free account and play 25 rounds of the main game first — the Arena assumes you already know the Doomsday algorithm, so the ladder stays competitive.