I see the MGSV mentions in this thread and I think some people really missed the boat with that game's level design, but it isn't necessarily their fault. The open barren world serves purpose in the context of the missions, but disappoints on its own without that context. The game allows you to play it how you want and that really allows some to play it in the least enjoyable way possible by staying in the contextless open world and not notice the effort put into the level design of the mission areas. MGSV allows you to skip the fun and embrace the tedium basically.
The bigger bases, while many are smaller or less dense than Camp Omega, are arguably just as well designed. They have tons of secret paths, hidden tunnels, and lots of more subtle paths made for the player. In the Mission 5 resupply base where you grab the bionic arm maker for example, there's a stupid amount of secret paths to find to each objective. Your first obvious way is the giant gate up the winding road, but if you look around you can climb the left or mountains at various point to get to the cliffs avoiding that. From there you can drop in to the underground area avoiding the patrol heavy stairs. There is a path that goes around the back of the barracks that allows you to get around an to those houses easily for any objectives there easily. And all these paths are highlighted with natural cues. Like the paths usually have grass leading right to them, rather than having to have signpost them with markers like most games. Unfortunately I think a lot of people miss the care put into these levels because they blow through quickly with a tranq gun or sniper and frankly don't need to. That's an issue with MGSV, in giving so much freedom it rarely pushes players to really engage with these levels. I'm fine with it but for a lot of players (watch the avg stream of the game) just do the same thing every mission, they find one path and that's always the path. They don't need to plan because they can reflex out of it or just run around like a madman ignoring all but the objective. They can skip the fun of planning, and sneaking around a base using the level design to the point where they never have to use a weapon. But just because they don't see that design doesn't mean it isn't there.
Like was mentioned earlier, the game can actually played like a series of Ground Zeroes maps, but it gives you the option not to. You can absolutely just play each mission like a mini ground zeroes. you helicopter in or nearby, start the mission, complete it, and either helicopter out or leave on foot and then use the menu to return to base. That's how I did every mission except for the ones during the outbreak on mother base where each mission was short and grouped very close by while the game encouraged a sense of urgency because all your dudes were dying. But you can skip the fun of just playing these fleshed out missions consecutively by running around a much emptier non-mission map trying to find the next mission and creating a lot of tedium between each. So then there's the complaint if that's how you play it, only dropping in and out of missions, isn't the open world wasted? And that's definitely not true. Each country has missions where the size is used for some amazing missions that wouldn't be possible in a game space the size of GZ.
Back up and back down, the mission where you have to destroy or capture as many Soviet vehicles as possible is a great example of the game utilizing the size of its world. You get this giant area, you can start on any end of, and it's up to you to plan how you ambush these vehicles, or if you want to just ride at them like a madman on your horse with an RPG while 80s music plays (like I did my first time). Here too, the game allows you to skip the fun of the level they designed. You can destroy one vehicle and complete the mission, you don't have to plan, you don't have to engage. The real beauty of the mission and level design appears when you start planning for how you're going to take out every vehicle and/or added objectives and that's something that really relies on great level design.
Maybe first you use D-Horse and you plan a route after seeing how the waves come in destroying them as you go, and you realize the best paths of the main road like going in the river to bypass the bases of enemies. While you do maybe you even find POWs, the game puts these guys in a lot of the shortcuts that will save you time. Like if you dropped into the southwest entrance there's a search team that goes right through the fast shortcut to the northeast searching for a missing POW. When you get to the extra set of tanks there are POWs in the sands you would take to get to the tank and avoid the base and outposts it patrols along. The level is filled with thought put into it like that. As you replay you may notice certain parts of the map naturally lend themselves to ambush points. With enough paying attention you learn that using some decoys and perching in those spots will allow you to take out everything. You may stumble into that on an early playthrough if you plan correctly. Trying to get all the mission objectives in one run is really fun by the way, especially if you do it early on before you get all the OP items.
Here's a video showcasing some of these paths and attention to detail in the level design through the level (unfortunately with end game equipment but its possible without that):
https://www.youtube.com/watch?v=TSyDke7KoZs
Backup Backdown isn't even the best example of a level that fully uses the large play area in MGSV. Arguably that's Mission 16, Traitors Caravan, which is just capturing a truck in Africa. Despite such a simple main objective this is probably the absolute highlight of MGSV's mission design, and it utilizes the huge space of the map for that mission. I don't feel like going blow by blow on it again at the moment but will if someone wants to argue it. But it again shows off the versatility of the design for these missions and levels. Same with Proxy War, Code Taker, Where the Bees Sleep, and Hellbound. You'll notice a lot of these levels have a timer either overtly or on a hidden timer. This would be frustrating in a new area with no context, but because you've usually been to some of these bases and terrain before it allows the player to be able to look at the big picture while having some idea of where to go and how to get there even if soldier patrols are different.
Oh and the the barren world should also get recognition with the new and more complicated alert system it is deeply tied to. By having a big empty area devoid of soldiers around the bases and main roads it allows the player to get out regroup or use the cigar to cool things down. This allows soldiers in the bases to stay alert for huge periods of time, unlike GZ where they forget they have a hostile breaking into their base in like 3 minutes, while still seeming fair to all players. If there were random soldiers and vehicles everywhere, trying to avoid and stay hidden could be extremely frustrating especially with later soldiers who can see much farther.
I also feel like if Ground Zeroes had a lot more development time than any one place in MGSV and also that players got to play it a lot more. If GZ had taken place somewhere like the Mfinda Oilfield, with six missions on it like Camp Omega and equivalent play time on it people would have gotten to know and appreciate the level design there a lot more and regarded it in a better light. This leads to another issue with context and how it colors perception. I think another reason is GZ praised over TPP areas is that it features context the player is more interested in. The mission features characters the player knows, and has cutscenes featuring them throughout. Whereas TPP missions, despite being well designed featured generic nobodies by comparison and very little in the way of cutscenes in mission. If the Mfinda oilbase was the prologue area mission space featuring known MGS characters and more GZ style cutscenes and then the GZ mission space was in TPP later on, along a cliff in Africa or something, with no cutscenes and only featured nameless POWs in place of Chico and Paz I think a lot of players would hold in similar regard to the rest of the game.
So anyway, it is absolutely on MGSV that it doesn't give enough incentives to play in a way that's fun and fully utilizes the level design, that it gives arguable poorer context for each mission to engage player interest, and didn't clarify or get rid of potential confusion about the best way to get to and from missions, but to say that the level design sucks, or isn't well crafted is just not true.
