You can relive the early days of computer gaming on your Arduino with Hunt the Wumpus.  This game is a particularly good fit for the RGB LCD shield:
  • Different screens can have different backlight colors
  • The LCD is large enough for selecting caves to move to or shoot into
  • The Wumpus, bat, and pit can all have custom characters
  • The D-Pad is well suited to handling menu navigation
You will need:

Of course, you do run the risk of taking a wrong turn and being eaten by a Wumpus!
While coding Hunt the Wumpus, I ran into a problem with one of my functions.  I wanted to use an enum to represent different hazards (bats, pits, Wumpus) and have a common function to check a given cave for hazards and return the enum of the first one found.  This helps with showing hazards in neighboring caves as well as checking a cave before the player moves into it.

I started by declaring a function which returns an enum:
HazardType check_for_hazards(uint8_t room_idx) {
  if (room_idx == bat1_room || room_idx == bat2_room) {
    return BAT;
  } else if (room_idx == pit1_room || room_idx == pit2_room) {
    return PIT;
  } else if (room_idx == wumpus_room) {
    return WUMPUS;
  } else {
    return NONE;
Unfortunately, this resulted in the following error message:
Hunt_The_Wumpus:-1: error: 'HazardType' does not name a type
It turns out that this is a known issue with a documented workaround and the fix was as simple as adding a header file Hunt_The_Wumpus.h to my project which contains the enum declaration and a function prototype:
enum HazardType { NONE=0, BAT=1, PIT=2, WUMPUS=4 };

HazardType check_for_hazards(uint8_t room_idx);
And including the file at the top of the main Hunt_The_Wumpus.ino file:
#include "Hunt_The_Wumpus.h"
Another interesting area of the code is related to reading button presses.  The RGB LCD shield library provides a function for reading which buttons are currently pressed as a bitmask.  For menu navigation, it's important to understand clicks.  By using a static unit8_t to store the last state of the buttons, it's possible to determine which buttons have been pressed and then released.  
void read_button_clicks() {
  static uint8_t last_buttons = 0;
  uint8_t buttons = lcd.readButtons();
  clicked_buttons = (last_buttons ^ buttons) & (~buttons);
  last_buttons = buttons;
Download the latest code on Github

Here's a 'diff' for monochrome displays!
*** Hunt_The_Wumpus.ino.orig 2012-11-24 12:43:10.936042927 -0500
--- Hunt_The_Wumpus.ino 2012-11-24 13:14:11.908126852 -0500
*** 42,47 ****
--- 42,48 ----
#include "Hunt_The_Wumpus.h"

+ #define MONO 1 // cheapskate with no RGB (or they were out of stock)

//! Map of the cavern layout.
*** 270,276 ****
--- 271,281 ----
//! Initial game state, draw the splash screen.
void begin_splash_screen() {
+ #ifndef MONO
+ #else
+ lcd.setBacklight(RED); // MONO backlight ON is on RED line
+ #endif
lcd.print(F("HUNT THE WUMPUS"));

state = animate_splash_screen;
*** 357,363 ****
--- 362,370 ----

void begin_bat_move() {
+ #ifndef MONO
+ #endif
lcd.setCursor(5, 0);
*** 429,439 ****
--- 436,448 ----

+ #ifndef MONO
if (adjacent_hazards) {
} else {
+ #endif

lcd.setCursor(1, 1);
for (int i=0; i-->"));

*** 575,581 ****
--- 590,598 ----

void draw_game_over_screen(uint8_t backlight, __FlashStringHelper *message, uint8_t icon) {
+ #ifndef MONO
+ #endif
lcd.setCursor(0, 1);

This guide was first published on Oct 03, 2012. It was last updated on Sep 19, 2012.