feature: ECTS basic mechanic

- add ECTS class to track balance and generation rate
- add ECTS and beer constants to settings

src/ects.py

@@ -0,0 +1,12 @@
+import pygame
+
+from src.settings import START_ECTS_VALUE, ECTS_UPDATE_INTERVAL
+
+class ECTS:
+    def __init__(self):
+        # total amount of ECTS the player has at the beginning
+        self.ects_balance = 0
+        # start amount of ECTS player gains ber interval at the beginning
+        self.ects_per_second = START_ECTS_VALUE
+        # timer when last ECTS was given to player
+        self.last_update_time = pygame.time.get_ticks()

src/settings.py

@@ -12,3 +12,11 @@ COLOR_DOOR_BEIGE = (245, 245, 220)
 COLOR_DOOR_BORDER = (100, 90, 80)
 COLOR_HP_BAR_GREEN = (0, 255, 0)
 COLOR_HP_BAR_BG = (50, 50, 50)
+
+
+# --- ECTS ---
+START_ECTS_VALUE = 1        # how many ECTS are generated at the beginning
+ECTS_UPDATE_INTERVAL = 1000 # time in ms = 1 sec
+
+BEER_BOTTLE_ECTS_VALUE = 2
+BEER_COST = 50