Firefight design for iOS fps. Modern Combat indeed.

iOS first person shooters have several limitations that change firefight design for these devices compared to traditional console/pc design standards. I plan on creating a design document that uses those limitations as a starting point, and expands upon them. Some of these limitations are: the shorter play sessions preferred by iOS gamers, the relatively small size of the screen, and the way the game controls.

People expect iOS gaming experiences to be shorter than those on console/PC. They want to get their fun in 15 minutes or less, often because people play iOS games while in transit, or while waiting for something else. It helps to try and divide your gameplay up into 10-12 minute chunks to ensure the players have a complete experience each time they play, and also to encourage them to come back and play the next level / section.

The iPad has made screen resolution problems less of an issue – for iPad gamers. As iOS game designers we now have the challenge of making something compelling on the small iPhone screen that holds up on the larger screen. Basically we have to design firefights around the iPhone screen, and let the better graphics/effects carry those firefights onto the bigger screen. Designing for iPhone means that enemies must be large enough on screen for us to recognize them. As long as these enemies are recognizable we know they can be targeted easily using the ironsights zoomed-in aiming mode. We found on Modern Combat 3 that enemies couldn’t be more than 25-30 units away before they got too small to notice/target.

The first person control scheme developed here at Gameloft is one of the best on iOS. We have a modular system that allows the user to adjust the positioning and scale of each of the buttons. This lets players pick the layout that best suits them, but it also means we cannot assume which part of the screen is going to be covered up by their thumbs/fingers. Because of this we must prioritize action in the center of the screen, and avoid having action/information occur in the bottom corners of either side of the screen. The way the game controls also means that having action occur on opposite sides of the character is nearly impossible, 180 degree turns are not easy to perform and can take several finger swipes.

Consider the field of view, FOV is the extent of the observable world seen by the camera at any given moment. Average human FOV is close to 180 degrees left to right, though much of that is peripheral vision. (vertical FOV is closer to about 100 degrees). In games the camera usually has a FOV between 90 and 110-120, horizontally. I would estimate that the average left to right finger swipe moves the camera less than 90 degrees, making a 180 turn a matter of at least 3 swipes. This has to be taken into account, especially considering that going into ironsights mode further reduces the ‘rotating speed’ of the player.
All of these limitations affect what the user can see on screen at any one time. I call the playable space that these limitations leave behind the field of play, or FOP.

By understanding the field of play we can better decide how to set up encounters: enemy placement, spawn order etc…

With these limitations considered, I think a great place to begin looking at firefight design is not in fps games, but instead in rail shooters. Before I do this let me stress that I am not arguing that iOS fps need to be reduced to rail shooters. I think there is lots of room for player control, it makes the combat experience more dynamic, and it adds more strategic and exploratory gameplay for the user. But to try and create a fun playing experience let’s take a quick look at rail-shooter designs and see what we can learn from them.

Rail shooters often allow the player a (at least temporary) safe spot to take cover. Think of the ducking mechanic in Time Crisis. The rail-shooter moves the player from set piece to set piece, but in almost every instance there is a piece of cover the user can duck behind.

The enemies in rail-shooters always present themselves before they start attacking. Either by popping up from behind cover, or running in from the side of the screen, the user has a moment to first identify where the most imminent threat is, then to quickly map out the order he will target those threats.

Rail-shooters also play with resource management, giving the users limited ammo, or at least limited ammo for more powerful weapons, as well as offering occasional health packs and the like.

In Modern Combat 3 we learned that ducking is not the optimal way to offer the user a safe spot. The simplest way is to place high covers, where the user is covered while in standing position, and having the player strafe in and out of that cover by dragging their virtual joystick from left to right. This is easier in practice than having the user try and use the duck and pop gameplay of a gears of war.

Because of the limitations of the FOP we cannot have too many instances where the user has to swing their view to extremes in either direction. So when we present enemies we need to make sure they either pop-up within this FOP or run into this FOP from either side, and don’t start attacking the player until they have a chance to notice them.
We can certainly spawn enemies to the extremes of where the player is facing, but we need to limit the number of times we put the player in a position where they have to rotate the camera close to 180 degrees because “something” is shooting at them.
We can also play with resource management, though we do this equally to heighten gameplay by increasing the value of each bullet, while also recognizing that we will be selling ammo packs and upgrades via micro-transactions. Because of this economy we have to ensure that there is no level where the player will be unable to finish without micro-transactions, but we also want to make these purchases feel necessary. A fine balance s needed, one worthy of discussion on it’s own.

To be continued…


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