The indie horror The Backrooms: Lost Tape has a rather interesting reference to Half-Life, which also affects the plot. In the second episode (which was released on August 29 this year), the plot is focused on the SCP Foundation employee Nikolas, who is looking for his missing brother in the monstrous dimension The Backrooms. As he progresses, the main character will find himself on Level 52 "The School Halls", where he will discover an artifact that is iconic for the first part of Half-Life, also known as the Xen Crystal. As in Half-Life, the Xen Crystal will have quantum teleportation and by connecting the Crystal to the necessary equipment, it will help to move from the level. We can say that the developers of the game quite authentically wove a piece of Half-Life into the events, hinting at the existence of multiverses. It is worth noting that in the game itself, the famous SCP Foundation is engaged in the containment of anomalies right in The Backrooms. Here's a note confirming that the mineral that would help the protagonist escape Level 52 was the Xen Crystal. Agree, quite an unusual Easter egg for indie developers.