Monday, October 21, 2013

Game 4: "RunJumpDuck" released!

And we are done with game #4 - "RunJumpDuck". We tried to make a martial arts style platformer this week. It was MUCH harder than expected. By far the hardest genre we attempted so far for both of us. So what we have now at the end of a week is not a game yet, it's a prototype. Here is a video:


I love platformers and they seemed easy to make. Man was I wrong. Five days into the this game I had nothing to show, and Liza had nothing to show. We were both banging our heads at the buggy, poorly documented, awkward softwares and tools. But let me start a few days before that.

Last Monday we sat down to brainstorm the game design. There are a few good platformers in App Store, such as League of Evil and Fancy Pants. I really like the avatar action in Fancy Pants, so I wanted to make a platformer with similarly evocative movements and precise controls. The level design we decided to do using tiles, because we could iterate on them much faster than if using hand drawn levels. And given my martial arts background I wanted to have a martial arts theme.

One obvious question is how to design levels for a platformer. For our previous games, all level design was stored in the code. But for this game that wouldn't work, - levels are big, varied, with lots of unique details. So I needed a level editor. There are a few options: LevelHelper which reportedly is very buggy, another editor only for Windows, and the open sourced Tiled. Not much to choose from, Tiled was really the only option. But Tiled has poor documentation, and on the Mac obtuse and buggy UI.

So I made a level in Tiled that is saved as xml or json. But the game needs to read in this data, display it, move the camera, etc. No way I could write all this code in a week. Thankfully when using Corona SDK there are a couple of options here as well: Ceramic Tile Engine and Million Tiles Engine (MTE). The former is open source (awesome!), beta release, while the latter is inexpensive, proprietary, also beta release but more fully featured. I went with MTE for its features. The engine is nice, the developer very responsive in the forums, but it's still a beta quality software with an occasional bug and sparse documentation.

It took a couple of days to get my first attempt at a level to display on the phone. And just when I thought things would get straightforward and easy, they got MUCH harder:

A platformer needs physics to simulate the dynamics of the game. Some folks write their own physics engine, but I thought why waste time when a great physics engine Box2D is bundled with Corona? ... In a couple of days I would pulling my hair out in frustration at Box2D. Here is a sample of issues I ran into:

  • There is a fundamental flaw in Box2D that sometimes can abruptly stop a polygon (e.g. an avatar physical shape) sliding on smooth surfaces (e.g. ground) made of several tiles. Took two days to solve. I posted the solution here.
  • Avatar needs different physical shapes in different postures, eg. walking versus sliding. Changing shapes midway can make the avatar fall through solid ground. Solution requires very careful positioning of physical bodies in relation to each other.
  • Flickering tile edges because of scaling. Solved by extruding tiles by 1 pixel, and completely redoing the tilesets and the level map.
  • Fully testing the game in the simulator using the mouse is impossible. And hooking up key events to the simulator on Mac requires a paid subscription to Corona Pro.
  • ...
All of these are well known problems in making a platformer. But as a new comer to the genre, these were a little too much to solve in just one week.

These were my woes this week. Liza had just as many of her own:

Art for a tiled platformer consists of three parts: a tileset for levels, UI and avatar/NPC spritesheets. Way too much for one week. So we decided to buy the level tileset and the UI, while Liza focused on learning to animate characters. It's a story of obtuse, poorly documented software. She tried two inverse kinematics animation softwares: Spine and Flash. Both sucked. Out of seven days she spent five fighting the softwares, and only two animating.

I love the white ninja that Liza animated. And this is her first try at animating ever! There are many more animations she did that are not shown in the video above. I hope they will see light one day.

So in the end I am impressed that we were able to put together even a basic prototype. But the full game would take a few more months to develop.

P.S. And I can't post the source code because I am using proprietary engine MTE and licensed tilesets :(