so I recently downloaded both unity and visual studio after a fresh windows install, and visual studio already has the “visual studio tools for unity” but it doesn’t seem to be highlighting keywords like system, serializable and also it doesn’t auto complete some keywords.
Try the steps here: Intellisense Not Working with Visual Studio (Fix)
still doesn’t work,
Finally got it working, the problem was that in order for intellisense to work you need to switch the external editor from open by file extension to visual studio
Yes this was step 3 in the thread I shared above.