Not only is it a 1:1 port of Lionheart the author has added the demo levels and his own levels plus extended the tileset and engine capabilities. Because it is written in JAVA it works on Windows, MacOS, Linux, Android etc.
I don't know what that is in reference to but have you played the remake or just seen the screenshots on the website? In standard mode it plays pretty much 1:1 It's not emulation so it won't be frame for frame perfect but as close as necessary. If it isn't report it as a bug and it will be fixed immediately