Legacy follows a strict time system, and time in the game continues forward even if you don't log in and play.
Basically, 1 real day = 1 month in the game. So, 12 real days = 1 year in the game.
In order to have a system like this, the game uses a ‘rollover’ system to advance time in the game every 12 hours. Yes, that is every 12 rather than 24 hours. Each 12 hour rollover period will represent 2 weeks in the game. So, 24 rollovers happen in 1 game year. The current game month and year is noted in the upper right corner of the game.
Rollovers will occur every real day at noon and midnight Eastern Standard Time (EST/ET).
Horses will age based on the passing of the game's time. This means things like: foals will be born 11-12 real days after a mare is bred, foals will reach 2 years old (riding age) after 24 real days, and it also means horses will age and die in the game, among other things.
This also means you can train your horses 2X a day, if you want to.
The game will advance 2 weeks. This means horses will age 2 weeks, their training sessions will reset, and shows will run. Autotrainers or autoexercisers will also do their work during rollover, so you will get their bill, as well as other stable management bills (feed, barn upkeep, farrier bills, etc.).
The main reason is to ‘level the playing field’ between players, or, in another way, to increase collaboration and competition between players. With a time system like this, no one will be able to binge-play the game for hours one day to get ahead of other players. Which, we realize stinks in some ways, but this also means we will experience the game together at the same pace. This should hopefully increase collaboration across ranches, and increase our collective joy when foaling season arrives!
In real life, horses are seasonal breeders, and they breed in the months where daylight is long. We have simulated this in Legacy, and breeding season will last from May-September in the game. See the Fertility/Breeding Wiki page for more information.
At the top right of the screen you can see the current game month and the year (Y#). We know it's a little strange, but the game's years start in December, rather than January. So, you will see something like November Y10, then the next game month will be December Y11. No, it's not a bug, just a little weird thing with the code.
Your horses will continue to age, and foals will be born if you have pregnant mares. If you have autotrainers on, they will continue to work, and get paid, until your horses cannot be trained anymore. Your horses will also be fed automatically while you are away, just be sure to set them on the correct feed, or they could lose or gain weight unintentionally!