Bigger Game Worlds Aren't Always Better!
It seems that a lot of developers are using a rather flawed idea: "make the map as big as we can!"
This often seems the case with a lot of the Indie Early Access games found on Steam. A lot of them are survival games that offer you massive worlds for you to explore! Although the only experience I have had from DayZ, for example, (this was the mod for Arma 2, not the standalone version), was running away from zombies for 45 minutes in the dark until I found an axe only to get shot by a sniper through a window. I never actually met up with the friend I planned on playing with because we had spawned on opposite sides of the map.
Problem with Large Worlds
The big problem with large maps is that you need to fill them with content. Games like Skyrim and Fallout both have large maps, although they did not seem as big as you always come across things to do, such as going into a cave full of bandits or coming across Tenpenny Tower.
The only thing is that a lot of games with big maps only go big to show off that the engine can handle the rigorous demands; this usually leaves the world feeling hollow. You may have a massive terrain to explore, only there isn't anything to do there. A lot of the open world survival games like Rust seem to have a lazy design, making it feel like they have given you a basic world and then set you to work to make content.
Instead of giving you a world and content, then setting you out to find more and more things to do. It is obvious in some cases that they are trying to create the next Minecraft, which is an unbelievable goal. Not even Everquest Next Landmark has been able to do this, and Landmark has Sony Online Entertainment developing it. (One thing they need to do is ditch the patch idea and allow people to use the entire map to build greatness!)
It is no way near as hard to create game worlds as it was a number of years ago.
There are now tools that allow you to generate areas to use after just inputting a few numbers, or even allow you to simply mold the terrain with in-engine sculpting tools. By making it easier for people to create games and the introduction of Steam Greenlight, which doesn't seem to have any consistency or quality control whatsoever, allows people to develop empty games. These then sometimes get put up for retail with only promises of what the game might contain if developer is able to finish it. We're seeing this a lot: early access or Kickstarter games have run out of money or even just motivation, and the developers have stopped developing the game.
It's a lot like filling a cup with water, the bigger the cup the more water you will need, if you pour the contents of a smaller cup into a bigger cup it won't fill it up.
Problem with Smaller Worlds
One of the biggest issues of using smaller worlds is that it is hard for a developer to allow the player to break from the chains and do what they want. Most games with small maps are very linear and don't allow you that much choice in what you experience. A good example of a game using small maps is Medal of Honor: Warfighter. This game holds your hand and objectives are so much of a checklist that at one point the game asks you to bomb a building that a sniper is hiding in, if you try to move on even if you shoot the sniper you get killed instantly.
TotalBiscuit (CynicalBrit) talking about linear aspects of Medal of Hono(u)r: Warfighter
Advantage of Large Worlds
The big appeal of large worlds is that the size allows you to break out of the linear boundaries of some the smaller maps from games like in Call of Duty and Battlefield. This gives the player the chance to go where they want to go, rather than feeling like the game is holding their hand and showing them where the developer wants them to go.
It is a lot easier to really connect to a world that is big enough to give you the freedom to roam around the map throughout the game. A great example of this is the Mass Effect Universe, this combines lots smaller areas into one big open world game. To this day, I would say this is the series I have had the most attachment to.
Advantage of Smaller Worlds
Obviously the potential content of smaller worlds is greatly reduced; sometimes this could be a good thing. It is much easier to fill a world with content if it has smaller scale. Then there are some genres that are more suited to it, such as platformers.
Not every game wants to copy games like Skyrim. Look at Thomas Was Alone, it has small levels and only takes 2-3 hours to complete. This is great for a game like this because if it had been any longer it would start to get boring, thus losing its charm. A long playtime would probably lead to most people not finishing the game.
It is still in Alpha on Steam Early Access, but H1Z1, the zombie survival game from Sony Online Entertainment, uses a smaller game world to that of its counterparts. From what I have heard it benefits from this, other than a few misconceptions which got blown out of proportions on Reddit, people's experiences with the game are positive.
As the map is not so big as games like DayZ, you can meet up with your friends quickly rather than having to travel for nearly an hour to meet up with someone. That is, if you even managed to get to the correct place or if they told you the right one.
Sometimes games with smaller worlds can benefit from this, take RTS games like Warcraft 3, you have lots of small maps which you navigate your forces around to complete objectives. If you were to make the maps much larger, it would start to become a pain maneuvering while keeping an eye on what the enemy is doing. This franchise evolved into World of Warcraft, the most successful open-world MMORPG ever made. It still has a higher number of players than any other game in the genre, and this is over ten years after its original release in 2004.
Large open world games are great and I would hate to see them disappear, although I feel that having a big game world just for the sake of it, causing players to get bored whilst traveling through a vast emptiness. One of the first things developers should question themselves when creating a world is "can I fill it?" If you don't believe you can, maybe you should think about making it smaller so that you don't have expanses where there is nothing to do.