Maybe it looks kind of honour-damaging or so but there are enough people out there that still want Horizons to develop thought don't play anymore for several reasons.
I'd be willing to donate money if there is clearly said it is used to pay a dev for implementing pets for example.
Put a kind of "x Dollars to go for month ..." at the page so people can see how much is necessary. I suppose it would not be too hard for such a strongly wished feature to get let's say 3000 Dollar or more per month in.