Probabilities 1 and 2 are correlated, so you can't multiply them.

Although, by multiplying them, you got a probability of 0.6, and the Manifold market on ASI existing by 2035 (34 traders) is trading at ~40%. So if the Manifold market is correct, then it's true that the existential risk from ASI before 2035 is ≤0.5.

Regardless, technically the post author claimed that the probability for existential risk from ASI before 2045 was ≥0.5, and only said that it's likely that better-than-human-AI would exist by 2035.

The book "You Bet Your Life: Your Guide to Deadly Risk" by Buff & Buff is a similar aggregation/breakdown of death statistics, though since it is a book it is not interactive. Perhaps you or other contributors could look through it for sources or inspiration.

1. Get a word and decide based on whether the sum of the alphabetical indexes (a=1, o=15, ect) is even or odd. To get the word, explain the above to the other person and then say you're going to ask a question of them that they must answer quickly (to avoid computing the answer and then lying). Then say "what's the name of your hometown" or something.
2. Both of you pick a number in secret. If the sum is even, you win. If the sum is odd, they win. Say the numbers at the same time to prevent cheating. Redo if someone stutters.
3. Rock-Paper-Scissors. Normally pretty easy to predict the other person's actions, but if the stakes are high enough both players will climb to high enough layers of I-think-you-think-I-think that it's equivalent to #2.
4. Pick a narrow axis like age, height, shoe size, latitude of birthplace, ect. Whoever has the bigger number in that axis wins.
5. This https://www.hillelwayne.com/post/randomness/