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The Twine 1.4+ runtime engine (that is, the 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|
|Current versions of desktop Chrome, Firefox and Opera||✔||✔||✔||✔|
|iOS Safari 6+||✔||✔||✔||✔|
Other browsers are not officially supported. Their adherence to these features is unknown.
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.