It is the best $20 you will ever spend right now (except, ahem, that engagement ring you got off the truck on Canal Street).
They have a sale right now for that price and so run to the nearest website and download it.
It works a lot like Hardball Dynasty, I am not sure who had the interface first. I did not like HBD mainly because the players are fictional and in a league with other people right off the bat you miss deadlines, get confused and frustrated and I gave up after a few weeks.
But Out of the Park uses a database of all MLB players from 1871 to 2013, plus some minor leagues and international leagues.
You control the settings if you play as commissioner as well as manager of one of the teams - the computer manages the other teams. You can set up the league to be historical teams, random and randomly distributed players from all eras, or a single season progressive. You can hold a draft of all players to start the league, and also decide to clear all rosters and re-draft.
The visual is not grand - a far cry from videogames, but engaging enough and building a team playing solitaire and competing is a lot of fun. You can set trades to be difficult to make, easy or average.
The fatigue works differently, and I am still working that out but it works in a reasonable way so far. You need the 40 man roster (with 15 being in AAA) though so far I have played without a minor league - you can have up to 6 minor leagues, or none at all. You can set divisions or note.
Koufax is hard to hit.
Not sure when or if I will play in any of the online leagues, but as a solitaire game it is VERY engaging and entertaining.