Controls are a critical element to a successful game. Bad controls can ruin otherwise good design but the reverse is seldom true. Today I am going to cover some of the major genres in gaming and try to describe some of the elements that are important to get controls right for each of them. I will also talk a bit about the preferred input devices used for these genres and why I think they have become the standard.
First Person Shooter (FPS)
Preferred Input Device: Keyboard+Mouse or Gamepad
The first person shooter is probably the most dominant genre in gaming in terms of sales and overall popularity. Call of Duty is a perennial top seller and niche subgenres such as stealth-shooting and sniping are a testament to just how broad the fan base is for these games. From its inception in the early 1990s on the PC, keyboard input was the most ubiquitous method of control. With advances in technology and more complex design, multi-level stages necessitated a precise method for quickly looking around and aiming; the mouse was more than capable of filling this role. Later, as the FPS made its way to home consoles, controls needed to be adapted to suit gamepads without sacrificing in game design. While I initially found gamepad controls to be a bit clunky, I think that this was more a reflection of familiarity with keyboard+mouse than anything else. I think both methods, when implemented competently, are capable of servicing both the novice and expert. While it is entirely likely one input method is superior to the other, I believe this difference is mostly negligible and only relevant in extremely high level competition.
What they need to do well...
Regardless of chosen input, the criteria for quality controls are the same: precision, responsiveness, and simplicity. Precision entails the ability to focus aim on a particular point accurately. If you are only able to aim in the general vicinity of a target in an FPS, the controls aren't doing their job. The best controls allow the most skilled players to consistently pull off head shots on distant moving targets. Responsiveness is a multifaceted criteria composing moving and looking. Quality controls respond instantly allowing for stopping from a sprint and making sharp turns a breeze. In more recent FPSs with heavy parkour elements, responsiveness in controls further means that the user will be able to enter cover, climb a wall, or hop over a ledge and will not perform the incorrect action. Further, looking in any direction while moving should be intuitive and not lag behind inputs. It should not take lead up time to look up or return to forward facing. Finally, simplicity is a broad category which quite directly means that a player should not have to enter too many inputs or dig through menus to perform basic tasks. Switching weapons should be fast and throwing a grenade shouldn't require a selection menu. Further, a player familiar with the controls shouldn't be at risk of accidentally firing the wrong weapon in tense circumstances (ie. putting the grenade button right next to the weapon fire trigger could easily lead to unintended explosions).
Preferred Input Device: Arcade Stick
With their infancy in the days when arcades represented the most cutting edge in graphics and hardware capabilities, fighting games were initially tailored to a joystick and button lines setup. More recently, fighting games have had to adapt themselves to gamepads to appease the home console crowd. Ultimately, I feel that the gamepad is a vastly inferior device for fighting games. Techniques such as 'pianoing' and 'sliding' which allow for seemingly superhuman speeds at pushing buttons can not be performed on a gamepad. On this, the arcade stick allows for a user to rapidly push several buttons in a row as they can line up buttons across the index, middle, ring, and pinky finger. With a gamepad, applying a non-standard grip can, at best, provide access to a maximum of three buttons at a time (and alternating to a different set of three buttons is less streamlined then with an arcade stick). A keyboard is probably the next best input method to the arcade stick as it can easily match in terms of button alignment but I think that it ultimately loses out on the precision that a joystick can provide. While I personally prefer a keyboard setup due to familiarity, I recognize that I would be at a disadvantage if I were a tournament calibre player (which I most definitely am not).
What they need to do well...
Fighting games are much less reliant on precision than FPSs; characters typically take up a lot of screen real estate and there is no need to be able to reliably target an opponents body part while moving. In fact, when the graphics are stripped away, most fighting games rely on large rectangular boxes to indicate what space a player is occupying rather then a precise correspondence to how the animation looks. Solid controls in fighting games are much more a function of buffering and intuition. As good players are constantly moving and hammering buttons in quick succession, it is important that the game recognize intentional combinations of movements for special attacks when they are entered. As such, the game needs to have a memory of the last few things that were done and recognize when a player has simply moved from a ducking position to walking forward and throwing a punch versus inputting the standard special move sequence to throw a projectile. The best games reliably understand the player intended action unerringly.
Real Time Strategy (RTS)
Preferred Input Device: Mouse+Keyboard
Real time strategies have been almost exclusively the domain of the PC platform which is almost certainly due to controls. RTS games have been designed with a mouse+keyboard input scheme in mind since their inception. As such, when an RTS is ported to a home console, the gamepad controls are invariably trying to mimic a mouse+keyboard setup. Unlike the FPS, I do not think that the requirements of quality controls can be met with a gamepad given current RTS design philosophies. Simple functions, such as drag clicking, are pretty much impossible to emulate on a gamepad with the same efficiency as a mouse+keyboard.
What they need to do well...
Quality controls in an RTS need to be able to blend broad sweeping actions with granular precision. A player needs to be able to select a group of units just as easily as a single unit. Beyond this, the best controls allow to easily select a subset of units from a larger groups (ie only riflemen from a mixed group of riflemen and grenadiers). Further, good controls should facilitate a player being able to quickly jump to points of interest on the map or particular production buildings. Because so many different things can be happening at the same time in a match, hotkeys need to be intuitive, context sensitive, and conveniently mapped. As such, a player should be able to rest their hand and access every hotkey they could want without flying all around the keyboard like a butterfly. One of the key RTS stats for professional players is actions per minute, as such, proper controls should be able to process as many inputs as a player can muster with each press providing a maximum of output for the player.
As usual with a listing like this, it could go on at lot longer but I will stop here. Some of the obvious genres I didn't talk about are flight sims and racing which both utilize unique input devices. While I doubt that 'controls are important' is much of a revelation, I think that pinpointing exactly what separates the good from bad is a worthwhile exercise.