Well I can’t really comment on ergonomics for computer games (it probably depends heavily on the game, but I play games very infrequently/casually, so I’m not the guy to ask), but for just typing prose, there are several things you can do to improve your technique and avoid injury (irrespective of keyboard).
0. See a doctor or physical therapist. I don’t think any of us here can give you true expert advice.
1. Make sure your wrists are as straight as possible:
(a) Set the angle of your keyboard depending on the height of the table relative to your chair/torso: if the table is high, you want a steep tilt, or if the table/keyboard tray is low (or if you put the keyboard on your lap) you want the keyboard to be approximately flat. Try to play with the angle by flipping up/down the keyboard’s feet, or even piling things under the front or back side of the keyboard, to get it to whatever angle lets you keep your wrists straightest. Adjusting the keyboard angle affects how straight your wrists will be in the up/down direction. You absolutely don’t want to have your wrists bent upward or downward, which is the easiest way to injure yourself typing.
(b) Try to keep your hands & wrists & forearms straight in the left/right direction as well, by angling your hands a bit on the keyboard, so that your hands point straight ahead in the direction your forearms are pointed, instead of being angled outward (“ulnar deviation”). One thing that I find helps a lot with this is using my left ring finger to press the Z key, my left middle finger to press the X key, and my left index finger to press the C key. YMMV.
2. Make sure you are “floating” your wrists in the air as you type. Don’t rest your palms or wrists on a palmrest. Keeping your wrists and forearms in the air will allow you to take a lot of pressure off your fingers, and help you transfer impact shock from your fingers up to bigger muscles in your upper arms. Resting your wrist on something is also a way to put a lot of pressure on the carpal tunnel, which you want to avoid.
3. Try to type with a light springy style. Don’t bang away at the keys, but use just enough force to reliably actuate the switch. On Cherry MX switches, you may want to try to avoid even pressing the keys all the way to the bottom, but that’s not essential; the important bit is to never slam the key all the way down hard, as this causes a lot of extra shock on your fingers.
4. Try to keep reasonable posture:
(a) If you can adjust your workstation, try to get yourself set up so that your forearms are flat or even angled downward a bit, with your elbows at a 90° angle or greater. This isn’t quite as important as (a) for your fingers/wrists, but if you’re experiencing shoulder pain, it might help with that.
(b) Try not to slouch too much. Make sure you are either changing positions somewhat frequently or else sitting with your back straight and your head well supported by your neck. Leave your upper arms hanging straight down at your sides, rather than sticking outward or forward.
5. Try to take breaks whenever you can. e.g. stop typing and rest your hands for a bit every 10–15 minutes, stand up and stretch or walk around a bit every 30–40 minutes, don’t work continuously for more than a few hours at a time, but go take a stroll or eat lunch or something.
A split keyboard where you can independently adjust the height/separation and three-dimensional orientation of each half of the keyboard can definitely be a big help for reducing the load on your wrists. But it’s not a cure-all, and there’s a lot you can do to make any keyboard more comfortable.
