As a developer for Ipad and Iphone, one of the dilemmas you are faced with is whether to sell a separate iPhone app and a separate iPad app or simply release a single universal app that works on both platforms. There are some benefits to each strategy, so it's not an easy decision. Here are my pros and cons for developing a universal app.
1: Apple encourages universal apps, so the chance of getting featured on their "Featured List" is bigger.
2: It's a lot easier to maintain one code base for a single project rather than two - especially when updating the app.
3: Customer satisfaction is increased, because customers don't have to deal with or buy multiple apps.
4: The increase in customer satisfaction could result in better reviews, translating into higher sales.
5: Services such as Leaderboards and Achievements are shared among the devices, so an iPhone player can compete against an iPad player and vice versa.
1: You cannot set individual prices for the iPhone and iPad version, since you're just releasing one app with a single price tag.
2: You can't see how your sales are split between the iPhone and iPad version.
3: App size will be bigger, because you include assets related to both versions. Apart from a longer download time, this is especially problematic if your app increases beyond the 20mb limit required to be downloadable on 3g networks.
4: You are missing out on earnings generated by people willing to buy both the iPhone version and the iPad version of the game. These lost earnings are obviously bad from a financial point of view (unless the consumer decides to provide extra positive feedback to your game as a result), but not from a customer point of view.
5: With separate apps, you potentially launch your game twice - once per platform.
This gives you two windows of great exposure (one for each platform) as opposed to one (for both platforms).
Some developers choose to release an individual iPhone version AND a slightly more expensive universal app. This eliminates some but not all of the cons listed. We chose a universal app for our game Beat the Bullies, which we have been very happy about.
“Make sure the most fundamental player action is fun. Build your game around this core mechanic.”
Most successful games are built around a simple, fun gameplay mechanic. This is the most fundamental and frequent action you perform as the player. If this action is boring or unfulfilling, it doesn’t matter how many twists or extra features you add to the game. They can’t save your game design.
This core game mechanic must be intuitive and relatively easy to learn, because learning a mechanic is never as interesting as utilizing it as a means to completing your goal. In other words, learning time should be minimized. In order to increase the complexity and challenge level as the game progresses and player skills improve, small extra features also known as “satellite mechanics” should be introduced. These provide twists to the core gameplay mechanic, forcing the player to use it in a slightly different and more challenging way.
Game developers should minimize the learning time of these satellite mechanics too. This can be done by making sure that they are connected to the core gameplay mechanic in a logical, intuitive, and meaningful manner (see the first principle on “Meaningful Play”). The trampoline in Super Mario Bros. is a great example. Its function instantly clicks with you. You understand why it’s there and what it does – its implementation is meaningful. You might also want to minimise the amount of satellite mechanics, so the player doesn’t have to learn new ones constantly. In particular, if two mechanics have similar functions – if they are relatively redundant - delete one of them from your game. Or perhaps you can redesign one of them to have multiple functions (i.e. a lightsaber that can both deflect lasers and cut through enemies in close combat). Nonetheless, it’s important to beware of “feature-creep”! Kill your darlings! Don’t spam your game with huge amounts of satellite mechanics – that approach will just increase learning time.
Once all the satellite mechanics are introduced, make sure to switch them up in order to create a varied gameplay experience. Avoid using one for a while in order to renew player interest in it. If several satellite mechanics work together in interesting ways, exploit these relationships to bolster gameplay variation even further.
Principle found in: Angry Birds
Angry Birds is based on a single core mechanic: catapulting birds towards pigs. This action must be done hundreds of times in order to complete the game, and it’s very easy to get to grips with. Even small children understand the logic behind catapults. In order to complicate gameplay, various satellite mechanics are gradually introduced. The inclusion of several bird types – each with their own special attack - is one of them. The placement of TNT barrels that explode upon impact is another example. And the fact that some objects give bonus points when hit also serves to make the game harder to master. These satellite mechanics are instantly learned and seamlessly integrated with each other and the core gameplay mechanic.
Read about all 8 game design principles here.