Much has been said already about the difficulties of converting a modern FPS or similar game produced within the last 10 years to VR (spoiler alert, it's very difficult). But what about converting a fixed camera, pixelated arcade game to VR? Let's talk about that.
Above is a couple of the first screenshots of Root Beer On Tap. Here the mechanics are largely unchanged between the two images, but the models have been swapped out and some animations added. For the first three and a half months of development, all of my gameplay happened in the level shown in the top picture. I had to first make sure that the mechanics were interesting and fun. Then, given that players can often do what they please in VR, I had to keep the game structured.
First off was the throwing of root beer mugs. When a player throws a mug through the room at random, it will react normally to gravity and fly in whichever direction it was thrown, eventually falling to the ground and breaking. Keeping the throwing strictly realistic when you're actually trying to play the game however felt incredibly frustrating. However, it's very difficult to throw something straight, keep it upright so that root beer doesn't spill, and still be able to throw with a satisfying amount of force. So when you throw a mug onto a bar table, it's trajectory gets straightened out down the path and it gets pushed upright so that the mug lands flat. The player still needs to keep root beer from spilling out, but there's less risk of a mug falling onto it's side due to impact with the counter, which was all too easy without this augmentation.
And while we're on the topic of spillage, in the original game mugs are always served to the customers filled to the top with tasty soda, but unless I wanted to disregard physics completely, this was not an option for a VR version of the game. A player in Root Beer On Tap will spill drinks constantly, and usually will only get about half to three quarters of the glass served to an NPC. To account for that the NPC's have a drinking speed as well as a walking speed, and will move backwards towards the exit only as long as there is still root beer to drink in their mug. This gives me as a developer more levels to pull when I fine tune the difficulty, as I can change both the walk speeds of the NPCs as well as how quickly they drink. This also penalizes the player for throwing willy-nilly, without thinking about holding the a glass upright.
So throwing and fluid physics are largely taken care of, but what about movement? Luckily, common teleportation mechanics present in current VR games translate nicely to the controls of the classic arcade game Root Beer On Tap is based on. There's quite a lot of debate within VR communities when it comes to movement options, teleport vs joystick movement, concerns over motion sickness vs encouragement to "get your VR legs", but I wanted Root Beer On Tap to be playable by as many people as possible, given that its short rounds make for a great introduction to VR.
These mechanics were smoothed out a great deal before I placed a single character model or "final" asset into the game, and continue to be tweaked throughout development. As a result, Root Beer On Tap feels fresh and interesting while still hearkening back to its classic roots.