How close will the devices be to the router? Wifi N stuff is usually good enough for most people, although I dunno what speeds you actually require. I've tested Steam's in-house game streaming through wireless N (N600 speed) with indie games on my old HTPC running off my bedroom PC and it worked well, but not any large or complex 3D games. You might want to look at wireless AC for best speed, although both the router and the devices you're connecting to the router will need to support wireless AC. However, AC only works on the 5GHz band (high speed but poor signal penetration through objects) so if there are too many obstructions (walls, doors, metal, etc) between the router and the devices, that can cause signal strength dropoff even at short ranges. I myself have an
Asus RT-AC66U router (I'm sure Asus has newer models out now) and I've been very happy with the speed of AC wifi on my Nexus 5 and HTPC (I can stream large files and do high bitrate video very well), but I'm kind of glad I live in a small place because although the router is placed more or less in the middle of my house for equal coverage toward the front and back of the place, it suffers greatly from signal dropoff at the farther corners and when I leave the house.
Powerline networking might also be an option. In my experience it's more reliable than wifi generally is (I'm living in a 13 year old house with good electrical wiring) but beware of the fact that you'll need a pair of adaptors for each device you want to hook up, and speeds are nowhere near what the box or model number implies. I have a
"500Mbps" powerline networking kit that I've only ever gotten less than 100 Mbps with (usually closer to 75Mbps most of the time) despite devices at both ends being rated for gigabit speeds. Still, it's fairly solid and works well for hooking up devices that have an ethernet port but have slow or no wifi capability at all like older PCs or game consoles (my PS3 and Wii both only have slow wireless G connectivity).
When it comes to streaming Origin and other non-Steam games.. you can trick the client PC into thinking games are locally stored/installed when they're actually stored on another PC across the network. What you need to do is set up file sharing and symlinks.
On the host PC, right click on the folder/partition/drive you want to let other PCs access, click on properties, click on the sharing tab, click on the advanced sharing button, and check the box for "share this folder". You should have
these settings enabled in control panel to ensure file sharing is enabled and working. On the client PC you should set up a symlink, which is like a fancy shortcut that Windows sees as an actual folder.
Here's a simple guide with a Windows GUI program to help you generate symlinks, and
here's more info and examples using the command line. What you want to do is make a shortcut in the right place that actually points to the shared folder from the other PC.
I've done this with Steam, but it should work for other games as well. How you need to set it up exactly depends on the game, and in Origin's case I think you should have the Origin client installed on both PCs, but the client PC's Origin game folder would be a symlink that actually points to the host PC's origin game folder which is being shared on the network. When done on the client PC, you have a completely seamless shortcut that leads to the shared folder on the host PC. You can log into Origin on the client PC and Origin thinks it sees locally installed games that are actually on the host PC.
As for performance.. Unlike Steam In-home game streaming where the host PC does the hard work and the client PC just receives the picture and controls, sharing game files this way means the framerate will be dependent on the client PC's own processor and graphics card. Streaming game files from one PC to another will be totally dependent on the speed of the network. Just like how a slow hard drive can bottleneck game loading times, a slow network connection can increase loading times of games being shared over the network as the client PC has to access the files from the host PC in order to process them.
For some games this isn't that big of a problem, but for some graphically demanding games and game types like open world games that feature seamless loading of game content on the go in the background (GTAV, etc), a slow network could cause stuttering as the client can't access game files to load and process them quickly enough. It's hard to say as I haven't actually tested it, this is just something that I think could happen.