======Browser support======

The Twine 1.4+ runtime engine (that is, the Javascript engine used to play built Twine games) has the following official browser support:

^ Browser ^ Basic Usage ^ Embedded Images ^ HTML5-based history ^ CSS Transitions ^
|IE 7  |Will not run| | | |
|IE 8  |✔|< 32KB each| | |
|IE 9 |✔|✔| | |
|IE 10+ |✔|✔|✔|✔|
|Current versions of desktop Chrome, Firefox and Opera|✔|✔|✔|✔|
|Safari 5.1+|✔|✔|✔|✔|
|iOS Safari 6+ |✔|✔|Only if private browsing is off|✔|
Other browsers are not officially supported. Their adherence to these features is unknown.

=====HTML5 history fallback=====

Since IE 8 and IE 9 do not support HTML5 History, they will fallback to the old hashstring-based history method used in Twine 1.3.5. Every time the player changes passages, a new hashstring containing an encoding of the current game state is added to the page's URL. This creates a new entry in the browser's history, and allows the back button to return to previous passages. However, it is bug-prone: whenever the back button is used, the entire page is reloaded and the game state is re-computed from the hash. This may cause certain custom macros (such as audio macros) to fail.