I would say investment is the closest of your 3 categories to describe Kickstarter. Although not by your definition of investment which is quite narrow, in that it only involves investing in companies for a share of ownership.
You give them money which has a potential return (the reward). They anticipate the return to be as described, frequently a slight discount to a good on a certain date. This return is very rarely estimated accurately as with most returns. Usually it is at least incorrect in the date estimate, sometimes the retail price price winds up being lower than the kickstarter price, and sometimes it exceeds the estimate and you get something like a free sticker too.
You are assuming risk with your money for that potential gain, that is the trade, like an investment just your money is a tiny amount, your risk somewhat mitigated, and your gain tiny.
You give them money which has a potential return (the reward). They anticipate the return to be as described, frequently a slight discount to a good on a certain date. This return is very rarely estimated accurately as with most returns. Usually it is at least incorrect in the date estimate, sometimes the retail price price winds up being lower than the kickstarter price, and sometimes it exceeds the estimate and you get something like a free sticker too.
You are assuming risk with your money for that potential gain, that is the trade, like an investment just your money is a tiny amount, your risk somewhat mitigated, and your gain tiny.