Why should I update to 1.0

From M.U.G.E.N Wiki

General

As the majority of players and developers are still using older mugen versions, I've decided to create a list of the most important problems that exist within the old winmugen and has been fixed in 1.0. In addition to these, you must also consider that winmugen will never, ever get an update, while mugen 1.0 is continuously updated and receiving fixes for newly discovered bugs.

Greatest problems with winmugen

• You can't change the resolution in winmugen. Mugen 1.0 supports any resolution your system can display.
• The ** operator in winmugen is bugged.
• There are problems with the sound plugins that can cause crashes while playing at random
• In winmugen, there is an elusive bug that can cause both players to stop or fly off the screen. This bug is triggered by P2 entering a custom state from P1's CNS file while P1 is already in the custom state of P2. In this case, P2 will end up in the state of the wrong player, and if that state doesn't exist, an invalid state. There are no proper workarounds for this bug (except for checking state numbers, guessing when it has happened, and trying to hit the opponent out of it using a fullscreen invisible projectile. The attack that was supposed to be performed still breaks anyway.)
• Winmugen doesn't support the game difficulty level setting for AI, so changing difficulty levels can be done individually on characters by editing character files. Not only is this very user unfriendly, but as there isn't a common difficulty standard, similar level settings can be very different in difficulty, so a balanced overall difficulty level is almost impossible to have.
• Winmugen doesn't support AI coding, and it must be done using one of the various workarounds. Improper or lazy implementation on some of these can result in false positives : The AI of the character turning on when a human player is playing.
• In Winmugen, executing Destroyself (the controller that removes a helper) doesn't stop the now no longer existing helper from executing its code. This can result in undetermined behavior, and crashes. This bug was the one responsible for all the seemingly random crashes. As long as you were using characters that relied on helpers for any moves, you could experience a crash any time.
• In Winmugen, a certain bug can cause the game to freeze when closing. You'd have to close it using the task manager manually.
• The lack of the Cond trigger makes eliminating certain sources of debug messages excessively difficulty, or nearly impossible. With the debug spam around, your character will create an impression of being buggy in players,even if it is working perfectly.
• The floating math used in winmugen was less precise.
• Winmugen didn't have proper stage recognition functions, so you had to rely on workarounds to be able to detect a stage specifically made with the workaround in mind.
• Hundreds of other, less severe bugs were fixed in 1.0 that are still present in winmugen. In addition, there are a large number of bugs and issues that will be fixed in the future in 1.0 or later versions, but will stay in winmugen forever.