The week-long digital event, which offers access to hundreds of PC game demos, is running until February 28 at 10am PT / 1pm ET / 6pm GMT.
As well as game demos, Steam Next Fest will include a series of developer livestreams and give players the opportunity to chat with creators about their games in progress.
Steam Next Fest was previously known as the Steam Game Festival, which originally premiered as a spin-off to The Game Awards in December 2019.
The company will distribute the first batch of order emails to reservation holders (in the order they were placed) shortly after 10am PT / 1pm ET / 6pm GMT on February 25.
Customers will be given 72 hours from receipt of their order email to purchase a Steam Deck or their reservation will be passed to the next person waiting.
“The first units will be on their way to customers starting the 28th, and we plan to release new order email batches on a weekly cadence,” Valve said recently.
Prices start at $399 / £349 (64GB eMMC), with increased storage options available for $529 / £459 (256GB NVMe SSD) and $649 / £569 (512GB NVMe SSD).