No matter how much level design I do, there’s still one thing that I have huge problems with - height changes. In particular, inventing ways to get a player from one platform to another much higher up (say, above the height of the player’s head) that don’t cause more problems than they solve.
My major maps (Dust and Cobble) don’t have this problem because I avoided it by keeping them flat, operating on only a couple of different planes with ramps inbetween. Cobble has a few horrendous components for getting players up and down these planes, in particular the thin ramp at the Terrorist start which was forced there through requirement rather than through want. Cobble also has ladders and abrupt height changes that don’t appeal to me partly due to the peculiar scale.
Sienna was a bit different, since the entire map operates on a slope. In some respects this made it easier since I knew there would have to be significant changes in height and was hence more willing to take risks. Sienna has five basic planes of height, with the Terrorists starting on the lowest and CTs starting on the highest, so it was unavoidable yet intentional.
Getting players between planes requires significant planning, particularly in a game like CS, since it is very important to ensure players can move quickly and effectively whilst also offering appropriate cover. A long corridor of stairs is one of the worst solutions in CS. Similarly, having the player head up flight after flight up stairs is something that will confuse and annoy unless done properly (I think Backalley handled it fairly well).
Changes in height also exposes the players to certain risks - consider heading down the Terrorist-side ramp in the Dust 1 underpass. You don’t know what sort of CT resistance there will be; if you casually walk down there’s a good chance you’ll be sniped within seconds.
The problem is even more apparent on very vertical maps, such as Oilrig (which has 6 or 7 planes) or even the new CS:S Assault (which has 3 planes separated by significant distances), since players must be able to get between the planes easily. Oilrig was quite contained and focussed on segregated ramps, whereas the CTs in Assault are fairly safe changing between planes because the Terrorists typically stay inside the warehouse where they don’t pose a risk.
I think the main issue is planning. Planning for height changes is tricky, but a few rules can help make it easier. Generally, ensure that it doesn’t take long for a player to get between two planes of your map; no more than a few seconds especially if they’re in a risky/dangerous area. Also ensure that a player is always presented with a way to get from one plane to another, or can determine one from their surroundings. Most importantly: ensure getting between planes is easy, quick, and that there is always an alternative if it is a major part of your map; one small staircase separating Terrorists from CTs will not cut it.
That’s the easy bit. The tricky bit is getting whatever mechanism you use to look good… (which I’m also very bad at)