As per my knowledge: "Buyers from Germany, Australia, New Zealand, Cuba, Sudan, Japan, Singapore and Yemen don't receive Manhunt at all. But the ROW Steam key for Manhunt is not region locked for activation anywhere."

Edit: on SG "Notice: ⚠️ Regional restrictions ⚠️
Manhunt
Official Humble Bundle notes:
Manhunt is not available in some regions. Please click here for more information.
Manhunt cannot be redeemed in AU, CU, DE, JP, NZ, SD, SG, SY, YE. (message shown on the HB download page)

What actually happens:
If you purchase the game from AU, CU, DE, JP, NZ, SD, SG, SY, YE, there will be no key provided on your purchase page.
If you purchase the game outside AU, CU, DE, JP, NZ, SD, SG, SY, YE, the key will be present on your purchase page and will activate regardless of your region, even in those countries listed above."

But thank you for your heads-up.