If you want to have a chance to participate in testing the game during alpha, you need to purchase the game by 31 March, 2019. Quote from a forum post by Renfail below.
"We are officially closing the pre-order store on March 31st, 2019
. Which means you have an extremely limited window to join us for the next stage of our journey: alpha. Once we shut down the store, those rewards are gone for good, and our Early Access community will be locked in throughout the entirety of the alpha stage."
In the post he also talks about introduction of NDAs, new investors coming aboard, etc.. Worth reading if you consider supporting / playing this game, in my opinion. Link below.https://sagaoflucimia.com/forums/index.php?threads/development-stage-two.974/