nDreams has been experimenting with virtual reality games for a year now, and has decided to focus heavily on VR games for the foreseeable future -- indeed, the studio currently has seven VR games in development. At Develop Conference today, nDreams' Patrick O'Luanaigh discussed the many dos and don'ts of VR game design that his company has discovered through its experiments with the Oculus Rift and Sony's Morpheus. "What makes VR so special? It is presence," he says. "The feeling of actually being there. When you put a VR headset on a player, they feel like they're actually there. You're teleporting them into your game world." This is the base concept that nDreams has focused its VR experiments on, including with its titles skyDIEving and The Assembly. "VR isn't about gaming - it's about experiencing," he adds. "You need to do things the player is comfortable with." With this in mind, here are nDreams' big dos and don't for developers creating VR games.

Dos

Keep every movement smooth - this is essential to keeping players immersed. Use 3D items to display information - rather than using standard GUIs, think about ways information can be displayed such that players stay in the experience. Maybe a watch on your wrist, or in the same style that games like Dead Space use. Use 3D text if you need it - if you need text in your game, make it 3D, and position it in appropriate areas. For example, if you want to call out an object and explain its function through text, hover the text over the object, such that the player will approach the object and read the text as they approach. Avoid 'what I know, but it doesn't feel right' - players know what feels right, and O'Luanaigh notes that, "as soon as you mess with that, players know that it doesn't feel right. It's the VR uncanny valley." "Walking and running need to feel real" - The average walking speed is 1.4 m/s," says the dev, and sprinting is around 5.5 m/s. Meanwhile, the sprinting speed in Call of Duty is around 6.95 m/s. Thus, using VR with Call of Duty doesn't feel slick because the running doesn't feel right. Turning is the same too - comfortable turning rate is around half a turn a second, yet turning in Call of Duty is 1.5 turns a second, so in VR it feels weird. Making your walking, running and turning speeds feel as close to real-life as possible to keep players immersed. Games have to be 1080p+ and 60fps+ - 60fps is particularly important, says the dev. "Audio is twice as important in VR" - so make sure you look into third-party audio solutions.

Don'ts

Don't assume it has to be first-person - nDreams has experimented with third-person games, and found they can work perfectly well if positioned appropriately. The studio put together a prototype called Spacewrecks which had you playing as a drone hovering above the action, with a character down below that you're controlling via the drone. This, says O'Luanaigh, felt really good to play. Don't assume you need a player body - many VR devs say that you need to have a body that the player can look down at in a first-person game, but O'Luanaigh notes that this is a whole lot of work. You need to match the player's skin tone, for example, and match their height to keep the immersion intact. It can be a ton of animation work, and is very difficult to implement, so it may not be worth the time and effort. Cutscenes with switching cameras - cutscenes that pull the camera away from the player can really bring you out of the action. Consider using Half-Life style cutscenes, which keep the camera firmly in the hands of the player. 2D Gui - Traditional GUIs don't work well at all in VR, says O'Luanaigh, and as mentioned above, it's best to think about how information can be displayed in better ways than a traditional interface. Don't use traditional keyboard controls - Players will not be able to find WASD controls in the heat of action. If you really need to implement keyboard controls, use the arrow keys and the space bar, as these are easier to find when you have a headset on. The game taking control of the camera - "It really makes people feel sick when this happens," says the designer. No camera bob - again, it's a case of making sure the player doesn't feel sickness. "When it's automatically bobbing, you can feel unwell pretty quickly." Throw players straight into the action - "They don't want to be part of the action straight away," reasons O'Luanaigh. "Let them explore first." Any sudden/snap movements - "Things don't happened suddenly in real life, so you really notice it in VR," he says. Hitting/collecting objects with your face - "When your face is flying into things, you become scared of it and try to protect your face." Thus, smashing into items is not a great idea for a VR game.