Supported operating system:

Windows Vista 32-bit
Windows Vista 64-bit
Windows 7 32-bit
Windows 7 64-bit
Windows 8 32-bit
Windows 8 64-bit
Windows 8.1 32-bit
Windows 8.1 64-bit
Windows 10 32-bit
Windows 10 64-bit

Release note:
New Features
1. OS X 10.11 El Capitan support has been added.
2. The SteelSeries Engine frontend now runs on Electron.
3. Performance loading device config windows is improved.
4. The GameSense SDK now has routines for deleting games and game events.

Bug Fixes
1. Fixed deadzones on the Stratus XL for Windows not being set correctly.
2. Fixed M800 games getting stuck when activated.
3. Fixed Launch Config key bindings not being reset correctly when configs are deleted.
4. Fixed crash when trying to set playback options on CPI toggle bindings.

New Firmware
1. Apex M800 - Fixed a rare issue where keyboard keys stop getting sent after a period of time on some setups.

Deprecated Support
1. OS X 10.7 Lion is no longer supported. Users still on 10.7 should either upgrade OS X or stay on SteelSeries Engine 3.4.4.1.
2. Windows XP does not work in 3.5.0, we are investigating possible fixes for it.

Supported Devices:
Predator Gaming Mouse
SteelSeries Apex 300
SteelSeries Apex 350
SteelSeries Apex M500
SteelSeries Apex M550
SteelSeries Apex M800 Dota 2 Edition
SteelSeries Apex Mechanical Gaming Keyboard
SteelSeries Dota 2 Gaming Mouse
SteelSeries Gaming Keyboard
SteelSeries Heroes of the Storm Gaming Mouse
SteelSeries HID Device
SteelSeries Kinzu v3
SteelSeries PS/2 Keyboard
SteelSeries PS2 Device
SteelSeries Rival
SteelSeries Rival 100
SteelSeries Rival 100 Dota 2 Edition
SteelSeries Rival 100 WoT
SteelSeries Rival 300
SteelSeries Rival 300 Fallout 4 Edition
SteelSeries Rival 500
SteelSeries Rival 700
SteelSeries Rival CS:GO Edition
SteelSeries Sensei Wireless
SteelSeries The Sims 4 Gaming Mouse