534- Ghost Hunter

This week we were to follow the tutorial and create a game called LadybugChase. It is a simple game in which the user is a ladybug, chasing aphids and avoiding a frog. The user uses the device’s Orientation Sensor to control the movement of the ladybug. It was somewhat similar to the MoleMash app we worked on earlier in the course, but more complicated. What was new in this tutorial was the following:

  • Using variables to keep track of numbers (the ladybug’s energy level).
  • Creating and using procedures with parameters.
  • Using the and block.

It was fun to build the app and realize that I am getting a better grasp of what different blocks do and how they can be used. When I finished the tutorial and was ready to begin inserting my own ideas, suddenly all blocks disappeared, and the only thing left was the information on the Design page. I looked everywhere for a solution only to realize that there is nothing I can do to restore them (I could contact the costumer support and ask for them to look at it from their end, but I decided not to). I posted my question also on the course’s Q&A page, and determined to re-build my lost blocks, followed the tutorial’s images to re-create it. I then tested it, and it worked well. I was ready to begin modifying the app.

I had several basic ideas, such as adding colors and buttons, and re-arranging and adding horizontal lines so it looks presentable. I changed the theme to a Ghost Busters type game with a “hunter” trying to catch a purple ghost while avoiding the black one. The two major changes I made was to create “Easier” and a “Harder” buttons. The first one adds power (time; to 260 pixels) while reducing the black ghost’s speed (x0.7) and size (also x0.7). The Harder button increases the size of the black ghost’s size (x1.5) and its speed (x2.5), and decreases the power to 150 pixels. Finally, I changed the sounds. I did not find it too difficult to make these changes. One thing that did not work was that after the game ends, when the user clicks “Try Again”, the images of the purple and black ghosts do not re-appear. I tried different ideas, but then gave up and posted it as a question for my peers. Lastly, I wanted to try something more challenging, so a Splash screen sounded good. I wanted to add a welcome screen with some images, a logo, and the instructions. I looked for some online tutorials, but could not find anything for AI2. I tried to follow and modify a tutorial for AI1, but it didn’t work…

Overall, I am quite pleased with this app. As I wrote above, I feel like I am getting a grasp on some of the elements, but the variables and procedures are still difficult for me to use freely. I also printed out the AI2 explanation chapters, and have read through them. One thing I find challenging is the fact that there is not enough support online for App Inventor 2. Most forums discuss AI1, and since there have been a lot of changes, they are not as helpful as I wished. Also, often times, the images we are asked to upload form the AI2 tutorial don’t work. It would be a good idea for them to go through and update the links on their websites.

Here are two images that show how I changed the app’s design. Unfortunately, the screen on my MacBook Pro shows the image slightly differently (for example, the red “Harder” button is not visible here).
LadyBugChaseScreenScreen Shot Ghost Hunter


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