feat(examples): add timer.rpy

https://www.fortunusgames.com/post/timed-choices-code

game/examples/start.rpy

@@ -38,6 +38,9 @@ label start:
         "Text":
             jump text
 
+        "Timer":
+            jump timer
+
         "Tooltip":
             jump tooltip
 

game/examples/timer.rpy

@@ -0,0 +1,38 @@
+# https://www.fortunusgames.com/post/timed-choices-code
+transform alpha_dissolve:
+    alpha 0.0
+    linear 0.5 alpha 1.0
+    on hide:
+        linear 0.5 alpha 0
+
+screen countdown:
+    timer 0.01 repeat True action If(timer_time > 0, true=SetVariable('timer_time', timer_time - 0.01), false=[Hide('countdown'), Jump(timer_jump)]) 
+        ### ^this code decreases variable time by 0.01 until time hits 0, at which point, the game jumps to label timer_jump (timer_jump is another variable that will be defined later)
+
+    bar value timer_time range timer_range xalign 0.5 yalign 0.9 xmaximum 300 at alpha_dissolve 
+        # ^This is the timer bar.
+
+default timer_time = 0
+default timer_range = 0
+default timer_jump = 'start'
+
+label timer:
+
+    label menu1:
+
+        $ timer_time = 3
+        $ timer_range = 3
+        $ timer_jump = 'menu1_slow'
+
+        show screen countdown
+
+        menu:
+            "End timer":
+                hide screen countdown
+                jump start
+
+    label menu1_slow:
+
+        "Did you fall asleep, by any chance?"
+
+        jump start