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Modifying Example Projects

A great way to learn LITIENGINE is to clone, run, and experiment with existing sample projects. This tutorial walks you through modifying SERVUS BONUS, an open-source 2D action game created with LITIENGINE.

1. Getting the Project

Clone the repository and build the project using Gradle:

git clone https://github.com/gurkenlabs/litiengine-ldjam44.git
cd litiengine-ldjam44
./gradlew run

2. Code vs. utiLITI: Where to Make Changes

When modifying a LITIENGINE game, changes are typically divided between Java Code (logic, controllers, physics) and the utiLITI Editor (sprites, animations, maps, entity placement):

Game Aspect Best Modified In How It's Configured
Movement Speed Java Code @MovementInfo(velocity = ...) on Entity class
Combat Cooldowns & Abilities Java Code Ability subclass or @AbilityInfo attributes
Creature Sprites & Animations utiLITI Editor Sprite Editor & Keyframe durations in game.litidata
Map Layout & Enemy Placements utiLITI Editor Drag-and-drop objects onto map layers

3. Practical Modification Examples

A. Adjusting Player Movement Speed (Code)

Open src/main/java/de/gurkenlabs/ldjam44/entities/Player.java:

// Increase velocity from 70 to 140 for double movement speed
@MovementInfo(velocity = 140)
@CollisionInfo(collisionBoxWidth = 8, collisionBoxHeight = 16, collision = true)
public class Player extends Creature {
  // ...
}

B. Customizing Attack Cooldown (Code)

Open the combat ability class (e.g. Hit.java):

// Reduce cooldown from 1000ms to 250ms for rapid attacks
@AbilityInfo(cooldown = 250, range = 24)
public class Hit extends Ability {
  public Hit(Creature executor) {
    super(executor);
  }
}

C. Modifying Spritesheets and Animations (utiLITI)

  1. Launch utiLITI and open game.litidata from the project directory.
  2. In the Spritesheet shelf, select monger-walk or monger-attack.
  3. Adjust keyframe durations (e.g. changing 100, 100, 100 to 50, 50, 50 to speed up the animation).
  4. Save the .litidata file and restart the game to see the updated visual pacing!

4. Next Steps