I thought it'd be nice to collect a lot of the bigger game engine-related differences, along with the sources for that information, in one place. It'll also help people who are either newer, or coming back, and have missed some of the subtle announcements. So I'm going to start adding to this post bit by bit; post here and I'll add the details to the topic.
Here's an IGN video interview where some basic info:
Enhanced Moves
In Injustice, some of the specials give you the opportunity to enhance the move with "meter burn" after the special has been hitconfirmed, rather than comitting to an EN move beforehand.
Hector Talks about Enhanced Specials
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Throw Techs
Throw tech'ing no longer depends on the direction of the throw. You can't tech throws during your recovery frames, or in a block-disabled state though (ex. being frozen).
Paulo, stream chat
Meter Gain
Meter built from blockstrings is based on the amount of chip damage now.
When damaging your opponent, you receive a percentage of their meter gain.
Paulo, stream chat
Wake-Up Attacks
The invulnerability window for wake-up attacks in IGAU is tweakable and varies per move.
https://twitter.com/pakostevens/status/297340293131415552
Blocking
Injustice is 100% back to block -- and block is not button-mappable.
https://twitter.com/pakostevens/status/299071937336987649
Injustice also features Pushblock, at the expense of 1 bar of meter:
http://www.gamerevolution.com/preview/injustice-gods-among-us/76943
Dashing
Dashes can no longer be cancelled into attacks or block. This includes the new air dashes, as well.
'Power Move' String Cancels, Dash-cancels
In IGAU, you have the ability to cancel strings into Injustice's Wall-Bounce and Stage Transition attacks at the expense of 2 bars of meter.
https://twitter.com/pakostevens/status/286944373168558080
Also, any normals that can be cancelled into a special, can also be cancelled to a dash by using the power/bounce enhancement and dashing out of it before it connects.
http://testyourmight.com/threads/rapid-cancels-what-stuff-do-you-want-to-try.27385/page-2#post-665175
Rounds
Injustice has a 'combined rounds' system, where 2 life bars are expended in a fight, with a short break as each player reaches the end of the first bar, with no 'life reset'. Note: This isn't exactly the same as one big life bar, because any extra damage is cut off at the end of the first bar; so no matter the damage of an attack, it will never spill over into the second bar.
Practice Mode
Injustice features recordable opponents in practice, as well as an online practice mode that allows you to practice with a friend.
Hector on Practice Mode
Controller Motion Styles
Injustice will allow you to toggle between traditional MK-style (D F) and SF-style (QCF - D. DF, F) inputs.
Hector Talks About Controller Options
Controller Config
You can now configure controls in the player select and pause menus.
Paulo, stream chat
Negative Edge Toggle
Negative edge -- the input that happens when you release a button you've already pressed, can be toggled on or off in IGAU.
Hector on Negative Edge
Stage Selection
Injustice features a 'coin flip' stage selection option, where both players make a stage selection and there's a 50/50 chance that one or the other will be picked. Each stage has multiple sections, and players can select the section where the fight will begin.
Game Updates
IGAU is expanding on the tweakvariables system introduced later in MK9; this will allow devs to tweak damage amounts, resets, frames etc. without having to release 'hard patches' for the game.
Hector on Tweakvariables
DLC Content Compatiblility
Injustice will require each player to download compatibility packs for newly released content before being able to join an online game. This will prevent the previous 'desync' and DLC mismatch issues.
Hector on DLC Content
----------------------------
Story Mode Prefight Mini-games
IGAU's story mode will feature mini-games before certain fights that will give you more/less health for the match or other advantages/disadvantages.
Hector on Prefight Mini-games
Here's an IGN video interview where some basic info:
Enhanced Moves
In Injustice, some of the specials give you the opportunity to enhance the move with "meter burn" after the special has been hitconfirmed, rather than comitting to an EN move beforehand.
Hector Talks about Enhanced Specials
---------------------------------------------------------------------
Throw Techs
Throw tech'ing no longer depends on the direction of the throw. You can't tech throws during your recovery frames, or in a block-disabled state though (ex. being frozen).
Paulo, stream chat
Meter Gain
Meter built from blockstrings is based on the amount of chip damage now.
When damaging your opponent, you receive a percentage of their meter gain.
Paulo, stream chat
Wake-Up Attacks
The invulnerability window for wake-up attacks in IGAU is tweakable and varies per move.
https://twitter.com/pakostevens/status/297340293131415552
Blocking
Injustice is 100% back to block -- and block is not button-mappable.
https://twitter.com/pakostevens/status/299071937336987649
Injustice also features Pushblock, at the expense of 1 bar of meter:
http://www.gamerevolution.com/preview/injustice-gods-among-us/76943
Dashing
Dashes can no longer be cancelled into attacks or block. This includes the new air dashes, as well.
'Power Move' String Cancels, Dash-cancels
In IGAU, you have the ability to cancel strings into Injustice's Wall-Bounce and Stage Transition attacks at the expense of 2 bars of meter.
https://twitter.com/pakostevens/status/286944373168558080
Also, any normals that can be cancelled into a special, can also be cancelled to a dash by using the power/bounce enhancement and dashing out of it before it connects.
http://testyourmight.com/threads/rapid-cancels-what-stuff-do-you-want-to-try.27385/page-2#post-665175
Rounds
Injustice has a 'combined rounds' system, where 2 life bars are expended in a fight, with a short break as each player reaches the end of the first bar, with no 'life reset'. Note: This isn't exactly the same as one big life bar, because any extra damage is cut off at the end of the first bar; so no matter the damage of an attack, it will never spill over into the second bar.
Practice Mode
Injustice features recordable opponents in practice, as well as an online practice mode that allows you to practice with a friend.
Hector on Practice Mode
Controller Motion Styles
Injustice will allow you to toggle between traditional MK-style (D F) and SF-style (QCF - D. DF, F) inputs.
Hector Talks About Controller Options
Controller Config
You can now configure controls in the player select and pause menus.
Paulo, stream chat
Negative Edge Toggle
Negative edge -- the input that happens when you release a button you've already pressed, can be toggled on or off in IGAU.
Hector on Negative Edge
Stage Selection
Injustice features a 'coin flip' stage selection option, where both players make a stage selection and there's a 50/50 chance that one or the other will be picked. Each stage has multiple sections, and players can select the section where the fight will begin.
Game Updates
IGAU is expanding on the tweakvariables system introduced later in MK9; this will allow devs to tweak damage amounts, resets, frames etc. without having to release 'hard patches' for the game.
Hector on Tweakvariables
DLC Content Compatiblility
Injustice will require each player to download compatibility packs for newly released content before being able to join an online game. This will prevent the previous 'desync' and DLC mismatch issues.
Hector on DLC Content
----------------------------
Story Mode Prefight Mini-games
IGAU's story mode will feature mini-games before certain fights that will give you more/less health for the match or other advantages/disadvantages.
Hector on Prefight Mini-games
