Buy the game via this paypal link:
If you like it, do nothing and you'll get the periodic updates. If you don't like it, email me, and I'll refund you, no questions asked.
I am aware this is not as convenient as an actual demo. On the flip side, you get to play all of the game and not bump up against artificial walls. And remember, this is an early development build. It doesn't even deserve to be called "alpha" yet. So if you think the game has potential but isn't there yet, don't worry. It will keep evolving and you'll get the updates.
Why only this PayPal link? Because game stores have their own refund policies and take their own cut, so I can't tell them to refund you.
So if you've been following the game but were waiting for a demo, I'd like to ask you: try it out. I guarantee you that you can un-buy the game again with maximum convenience.