Valve already showcased the potential of VR with Half-Life: Alyx gameplay reveal but we didn't have much idea about the system's restriction until the developers held an AMA on Reddit. As a consequence, the iconic Barnacles will be altered along with jumping.
VR systems certainly bring a new dimension of gaming but they also come with restrictions. Most notably, movement is not the same as on regular platforms, such as PC or mainstream consoles. This issue will persist with Half-Life: Alyx as well and the biggest impact will be seen through the iconic Barnacles and jumping.
For those who are inexplicably unfamiliar with Half-Life workings or the Barnacles, they are the aliens that hang from the ceiling and grab anything that moves below them. Then they proceed to pull it in and munch on whatever reaches their orifice .
Considering a large portion of the creature's mechanics is movement-based, fans used the opportunity to aks developers how they will work during the Reddit AMA.
The response was somewhat expected as Barnacles will no longer work in the same way for the player. They will not pull Alyx up in order to avoid player discomfort that would be inflicted by unsolicited movement. According to the developer response, there were experiments that involved moving the player but that did not go very well.
Another movement-related issue that is often encountered in VR is related to jumping. Freeman used to jump around many crates and other obstacles but Alyx will pull herself over them as a regular human being would.
Furthermore, "jumping" will only be employed over short gaps but it will look different even then, probably to avoid motion sickness. The same developer stated the players preferred dealing with such jumps with a "teleport-style movement" so it's probably just going to be a blink fest.