Apollo Justice Case 5 : Turnabout Substitution is a non-profit, fan made sequel to Apollo Justice, the fourth game in the Ace Attorney franchise, created by Ping' and his team for the PyWright engine.
An ambitious, seven hour long "finale" to the series, Turnabout Substitution is the most popular Ace Attorney fan game to have been released, and has received near unanimous praise.
It is considered by many fans to be as good as the original Ace Attorney games, with some going as far as to call it their favorite case.
Turnabout Substitution has been called a "triumph" by Cardiovore, creator of the acclaimed fancase Turnabout Scapegoat. It has caught the attention of a project manager working for a well-known video game company, and has even been featured in a popular video game magazine in the Netherlands.
It is generally seen as the standard other fan games are to be measured up against, and has inspired the creators of Turnabout Scapegoat, Justice's Memoirs, and many others.