EarthShakerDS is a remake of a Sinclair ZX Spectrum game written in 1990 by Michael Batty. The objective of the game is to collect all of the diamonds in each level, avoiding falling boulders, fires, etc.

When the game starts, a menu system appears on the top screen. You can choose:

• Start: start from the beginning of the game
• Level Select: select a level from the level select menu
• Custom Level: play a level created with the level editor
• Sound Test: play with the game's sound effects
• Level Editor: create or edit custom levels in the level editor

Navigate to the desired option using the up and down buttons or the Select button. You can page through the options more quickly by using the left and right buttons. When the correct option is highlighted, press A or Start to select it. The B button returns to the previous menu if a submenu is currently active.

Collect all of the diamonds in each level. When all of the diamonds are collected, a notification sound will play and the door - located somewhere in the level - will start flashing. Enter the door to end the level. You can be killed by:

• Blocks landing on your head;
• Walking into fire;
• Running out of time.

The d-pad moves around the level. The X, Y, B and A buttons will poke the block that is above, to the left, below and to the right respectively, without moving the player sprite. This means you can push boulders, collect diamonds, and so on, that are next to you without moving. This is a useful technique in some of the levels.

If you make a mistake and get stuck, you can press L and R simultaneously to commit suicide and restart the level.

Press Select to bring up a map screen and press Select again to switch back to the game. Note that you can only bring up the map screen once per life per level, so only look at it when you need to.

Press Start to pause the game. Press it again to unpause. While paused, pressing X exits the game and returns to the title screen.

The following blocks can be found at various points in the game:

• Bubbles can be pushed around. They can be pushed into fires to extinguish the fires. They can also be used to prop up boulders.
• Boulders fall if not supported. They can be pushed around.
• Diamonds can be collected.
• Fires will destroy boulders that land on them. They can be extinguished by bubbles.
• Jumping jelly beans give a time bonus.
• Teleporters transport the player from one location to another.
• Elixirs give an extra life.
• Soil is removed when the player walks over it.
• Wet soil behaves like normal soil, except it falls like boulders. Wet soil landing on the player will not harm the player.
• Gravity inverters switch the direction of gravity. Boulders and other blocks landing on the player when gravity is inverted will not kill the player. Gravity remains inverted until the gravity timer runs out. The direction of gravity and the remaining time are both displayed at the bottom of the screen next to the green "g".
• Barriers block your path. They decrease the amount of remaining time if you walk into them.
• Barrier controllers will destroy all barriers when they are themselves destroyed. Drop a boulder onto them.

The level editor allows you to create custom levels using any of the blocks from the game. You can test your levels in the editor and save them to your flash cart. You can even share them with other people by sending them the level files. Levels created in the editor will work in both the Nintendo DS and Mac OSX versions of EarthShaker.

The cursor in the top display can be controlled using the d-pad. Press A to place a block and B to erase a block. By default, the map of the current level is displayed in the bottom display. Use the L and R buttons to change the block that is added to the level when A is pressed. The possible blocks are displayed at the bottom of the upper screen, and the current block is highlighted.

The "Options" button allows you to change the colour of the boulders and doors and the type of soil and walls in the current level. It also allows you to clear the current level ("New"), try out the level ("Test") or quit the editor ("Exit"). You can switch back to the level editor from the test mode by either finishing the level, losing all of your lives, or by switching to pause mode (press Start) and then pressing the X button.

Lastly, the "File" button provides a file requester with the ability to load, save and delete files. You can load a file by entering its name using the keyboard or by choosing it in the file list and then pressing "Load". You can save a file by entering a filename and pressing "Save". The filename is used as the name of the level and can be up to 28 characters long. To delete files, choose the file in the file list and press "Del". Scroll the file list up and down using the buttons on the right of the list.

Note that you will receive no warnings when saving or deleting that you are about to delete or overwrite a file.

Level data is saved in "/data/EarthShakerDS/". The "EarthShakerDS" directory is created automatically if it does not exist. Levels can be played via the "Custom Level" option on the main menu. They can also be shared by copying the level file from one flash cart to another.

To play the game you will need a flash cart and a DS or a DS emulator such as DeSmuME. To compile the sourcecode you will need to install devKitARM and the WoopsiGfx library.

• Coding - Antony Dzeryn
• Original graphics, sounds, levels and design - Michael Batty
• Beta testing - Another World
• M3i Zero compatibility testing - Polomint

• http://simianzombie.com - Development blog
• http://bitbucket.org/ant512/earthshakerds - BitBucket page
• http://bitbucket.org/ant512/earthshakerosx - Mac port
• http://bitbucket.org/ant512/woopsigfx - WoopsiGfx library

Contact me at ant@simianzombie.com.