Change: Make tick length 27 milliseconds (#10607)

This makes a month last about 60 seconds, allowing the use of real-time units in game.

Co-authored-by: Niels Martin Hansen <nielsm@indvikleren.dk>

src/date_type.h

@@ -22,8 +22,8 @@ typedef uint8  Day;   ///< Type for the day of the month, note: 1 based, first d
 /**
  * 1 day is 74 ticks; _date_fract used to be uint16 and incremented by 885. On
  *                    an overflow the new day begun and 65535 / 885 = 74.
- * 1 tick is approximately 30 ms.
- * 1 day is thus about 2 seconds (74 * 30 = 2220) on a machine that can run OpenTTD normally
+ * 1 tick is approximately 27 ms.
+ * 1 day is thus about 2 seconds (74 * 27 = 1998) on a machine that can run OpenTTD normally
  */
 static const int DAY_TICKS         =  74; ///< ticks per day
 static const int DAYS_IN_YEAR      = 365; ///< days per year

src/gfx_type.h

@@ -313,8 +313,12 @@ enum SpriteType : byte {
 	ST_INVALID  = 4,      ///< Pseudosprite or other unusable sprite, used only internally
 };
 
-/** The number of milliseconds per game tick. */
-static const uint MILLISECONDS_PER_TICK = 30;
+/**
+ * The number of milliseconds per game tick.
+ * The value 27 together with a day length of 74 ticks makes one day 1998 milliseconds, almost exactly 2 seconds.
+ * With a 2 second day, one standard month is 1 minute, and one standard year is slightly over 12 minutes.
+ */
+static const uint MILLISECONDS_PER_TICK = 27;
 
 /** Information about the currently used palette. */
 struct Palette {