# Custom simulator and 'syscalls'

**URL:** <https://forum.makecode.com/t/custom-simulator-and-syscalls/2390>\
**Category:** Arcade\
**Created:** [June 11, 2020, 11:47am UTC](https://forum.makecode.com/t/custom-simulator-and-syscalls/2390 "2020-06-11T11:47:06Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![ksjogo](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.makecode.com/ksjogo/32/1054_2.png) [@ksjogo](https://forum.makecode.com/u/ksjogo)\
**Post date:** [June 11, 2020, 11:47am UTC](https://forum.makecode.com/t/custom-simulator-and-syscalls/2390/1 "2020-06-11T11:47:06Z")

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Is there some way to have interaction between the JS simulator and the game runtime?  
I would e.g. like to dynamically fetch data from the browser and integrate some external services.  
Probably needs code on both sides?  
Is there some extendable version of the simulator available somewhere?

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**Author:** ![richard](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.makecode.com/richard/32/5417_2.png) [@richard](https://forum.makecode.com/u/richard)\
**Post date:** [June 11, 2020, 3:56pm UTC](https://forum.makecode.com/t/custom-simulator-and-syscalls/2390/2 "2020-06-11T15:56:46Z")

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I’m afraid not; we do not allow extensions to add code to the simulator for security reasons. The arcade simulator is closed source.

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**Author:** ![ksjogo](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.makecode.com/ksjogo/32/1054_2.png) [@ksjogo](https://forum.makecode.com/u/ksjogo)\
**Post date:** [June 11, 2020, 4:31pm UTC](https://forum.makecode.com/t/custom-simulator-and-syscalls/2390/3 "2020-06-11T16:31:32Z")

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Are there maybe plans to open source the simulator at some point?  
I am planning to host it on my own site, so the user would already be exposed to my ‘evil’ js, so security shouldn’t be implicated further for this use case?

I suppose I could monkey patch the ‘binary’ js in the assets folder for now.

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**Author:** ![richard](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.makecode.com/richard/32/5417_2.png) [@richard](https://forum.makecode.com/u/richard)\
**Post date:** [June 11, 2020, 5:13pm UTC](https://forum.makecode.com/t/custom-simulator-and-syscalls/2390/4 "2020-06-11T17:13:23Z")

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There are no plans at this time to make it open source.

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**Author:** ![peli](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.makecode.com/peli/32/12_2.png) [@peli](https://forum.makecode.com/u/peli)\
**Post date:** [June 11, 2020, 5:25pm UTC](https://forum.makecode.com/t/custom-simulator-and-syscalls/2390/5 "2020-06-11T17:25:17Z")

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If you export your game to github, you will get a compiled version of the editor. With great hackery, you should be able to hook up `fetch` requests into your game. It’s not really a supported scenario now so it might be painful to maintain this.