System Shock. Now don't get me wrong, I love the first System Shock, despite all the things it's sequel improved on. However, the control scheme and interface is dogshit and makes it almost unplayable to modern audiences.
The interface is a click and drag type, similar to Ultima Underworld. Now, that actually doesnt bother me personally, I think it makes more sense to pick an item up with the mouse cursor and drop it into the inventory, rather than just automatically pick it up after running into it like a kleptomaniac track runner. However, the lack of mouselook on the native DOS version makes this a real pain in the ass, as you can be ambushed while interacting with the environment, and not be able to react in time to counter. If you want to play the game, I strongly advise you get the Enhanced Edition and use mouselook.
The HUD is a cluttered mess of gauges and icons that correspond to all the cybernetic upgrades you collect throughout the game. The game gives you two different HUD's to choose from that you can switch on the fly; one that monitors all of your life and energy levels, as well as your stamina and icons to activate your abilities, but it's completely unnecessary and takes up a lot of your view of the action. The other HUD being a scaled down version of the former. Unless you want to feel like a walking CRT monitor, I suggest you play with the latter.
And finally, cyberspace. Your neural interface gives you the ability to jack your consciousness into computer terminals in game to hack them and progress through the level or gain information, which is a really cool idea, but the execution is flawed. You fly through a series of neon wired, maze like rooms in first person, blasting security programs. The constant bombardment of colors and the slippery controls are disorienting, and the higher you set the games difficulty, the worse the controls get. That's right, the developers intended it to be bad.