usually you have to register (just use any email) and do some clicking and captcha. But beside that, no investment is mandatory.
many of those faucets have quite high minimum withdraw limit, effectively preventing to get anything in reasonable time. But the PipeFlare described here has no minimum limit at all.
and of course don't expect to get rich for click + captcha. Its really just some free cents.
So lets get back to PipeFlare faucet, as I was surprised how few clicks were needed to get some minimum reward.