Instancing

I used instances a lot with my recent csgo map, It comes with its fair share of both pros and cons depending on how you use them. I used them for entire buildings as well as small lamps and building signs.

For things like lamps/lights there is no real downside. They are excellent for throwing in as an instance, and if later your environment light changes, its a simple edit to have everything map wide to change with it, also good for things like light glows/sprites being too bright when changing the bloom on HDR.

Works out as such a huge time saver and helps unify a lot of things. And probably even more so on a company wide project.

For buildings, I like using them because I prefer working on large structures in isolation so I don't get side tracked with other parts of the level. They are also useful in source if you have buildings that doesn't sit on the 90 degree grid. So you can make it in an instance on the grid, but then rotate the instance in the main map so its off the grid. any changes you need to do can then be done in the clean instance file.

The problems mostly kick in later when you are trying to do a proper skybox or using hint brushes and area portals for optimisation. You can either connect portals/hints in the main map with the instanced geometry, or add them in the instance with the building you are optimising. Both methods feel like a very messy way to work.

Also vis groups don't work with instances. If you click on the group to hide all props for example, it will only hide ones in the main map file. Anything inside an instance will stay making things a little more awkward.

This was all done in a multi player setting so I didn't have need to instance any single player elements, but I imagine this is where they will become most valuable.