Why did the early bird bonus go from 24hours to 6days?
Because, this probably was an error. The ICO rules
https://www.antshares.org/en-US/Blog/Details?id=21 which were available before the ICO started mentioned that 120% bonus will last from 8 August to 13 August. I was surprised when I saw that the bonus will only last 24h, now the bonus lasts for the duration that was specified before the ICO starts, so everything is back to normal
.
The OP says Antshares has the world's 1st refundable ICO. After reading it I interpreted it to mean you could reclaim your invested Bitcoins before the end of the ICO up to the point where the coin launches.
Crypti offered almost that same deal through Bter during its ICO so its probably not the world's 1st refundable ICO. You could buy into the Crypti ICO on Bter, then sell your stake for exactly what you paid for it up until the coin's launch.
There is more to that
refundable feature. After the end of the ICO and until the launch of the mainnet, any investor can claim their investment back if they feel, for instance, that ANS is overpriced.
