So, WarpWallet is a so-called brain wallet for Bitcoin. That is, you only have to remember a relatively short password and it generates the corresponding private key for use. It uses a memory and CPU hard set of cryptographic algorithms to ensure that brute-forcing is slowed way down. That is, when generating the private key, it takes considerable time. Their Javascript implementation takes over 10 seconds on my machine.

So the makers of it had challenges setup. By the time I stumbled on it, only the last challenge was left, with 6 months remaining. For that challenge, the reward for cracking an 8-character alphanumeric password was 20 BTC (and BCH and BTG!), which was worth over $100,000 USD at the time of the challenge end date.