A downloadable game for Windows, macOS, and Linux

Use your grappling hook to hurtle through the air and complete the course in record time! 

Move the mouse to aim and click to grapple.

Press WASD to boost in a direction.

If you hold the mouse button down, the grappling hook will automatically attach to the next surface that comes in range.

If you play through the itch.io app, you can participate in the online leaderboards.

This was an entry for OpenJam 2020.

Source code at https://gitlab.com/rcorre/jethook.


This game contains assets from many authors. See Credits for details on the assets and their licenses.

Assets not mentioned in Credits were created by me, and are licensed as follows:





  • Applause sound by Bansemer (CC0)
  • Wind sound by LolitaPerdurabo (CC-BY-3.0)
  • Boost sound by TiesWijnen (CC0)
  • Menu Select sound by LittleRobotSoundFactory (CC-BY-3.0)
  • Menu Change sound by victorium183 (CC0)
  • Lap Complete sound created with bfxr


jethook-linux-beta.zip 28 MB
Version 13 Feb 07, 2021
jethook-linux.zip 28 MB
Version 1 Jan 22, 2021
jethook-windows.zip 27 MB
Version 1 Jan 22, 2021
jethook-osx.zip 28 MB
Version 1 Jan 22, 2021
jethook-windows-beta.zip 27 MB
Version 13 Feb 07, 2021
jethook-osx-beta.zip 28 MB
Version 13 Feb 07, 2021

Development log


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Optimization is poor, unfortunately, though understandable. Didn't figure out how to progress to next level (record time seems too high for an entry level), graphical bugs after playing for a while. Other than that it was a fun experience!

Thanks for giving it a try @Hamzak! I’ve found that turning off SS Reflections (in the settings menu) can help a lot with performance. It will be off by default in the next release. Turning off motion blur can help too, and worst-case you can reduce resolution (though admittedly I need to do some optimization too).

The second level is actually disabled because it wasn’t quite ready yet. I don’t plan on barring entry based on your record times, those are there more as a goal. Also, the next release will feature online leaderboards when you play through the itch.io app, which hopefully will provide more variety in record times.

Mind sharing what graphical glitches you encountered?

(4 edits) (+1)

Sorry for the delay (mail considered notification a spam so...). There is the bug I was talking about and it was quite easy to reproduce. Just playing through the level, back to title, play again, back to title and bam:

Yeah, turning off reflections and motion blur helped a lot, but the game's still unplayable at full HD on AMD Ryzen 7 3700U (integrated graphics btw) as it is fast-paced. I don't mind switching to 1280x720 and I do this on every game (just for consistency), even though most of them work fine even on native resolution, but I suppose either some optimization or triple-buffered v-sync for relatively smooth 30 FPS would be a game-changer, but I also Don't suppose that such v-sync would be possible to implement or that there is anything to optimize due to overall graphics simplicity.