DOS Games can be among the most difficult video games to get running. Even if you get the game running, you still have to consider things like getting the sound working or calibrating the joystick.
A DOS Game is about the whole experience, from procuring a game to reading the documentation, installing the game, configurating the OS and software as need be, and finally running it.
The first point is that any DOS game originally came on floppy disks or on CDs. They generally came in a box with at least an instruction manual and a reference card. The instruction manual told you how to play the game, the reference card how to install the game. Somewhere inside the package would be the means to pass the copy protection question(s) the game would ask, if any. If the game had disk-based copy protection, the original disk(s) would be required to play the game.
I dislike the modern way of packaging DOS Games, namely as directories after a full install. There are games that only install certain options from the floppies. Other games have lesser-used options that tend to get left out of the configuration options. By only giving the resulting install, the options are limited to whatever the distributor thinks the gamer should play. Giving disk images is the best way to ensure that a game can be installed properly on any system, real or emulated.
Second, in order to play a game, you have to have a basic understanding of how the operating system works.
Generally the install instructions will tell you how start the game, but this assumes that you always start where the instructions assume you are in the operating system. DOS is, as its name suggests, a disk operating system. In the beginning, DOS (versions 1.0-1.25) could only manage floppy disks. DOS versions 2.0-3.31 focused on adding support for new hardware features and larger floppy and hard drives. DOS versions 4.0-6.22 focused mainly on adding new applications and utilities, but also added greater memory configuration options. DOS games tend not to focus on the version so long as the version has the resources it requires. However, the higher the version, the more memory the OS requires. It is commonly understood that DOS 5.0 offers the best balance between features and memory usage.
So, having your operating system in place, the player needs to know how the system works. In the most basic configuration, DOS assigns drive letters to each disk drive, whether floppy, hard, CD, tape or network. Floppy drives are A: and B:, the first hard drive is almost always C:, and the first CD drive is gnerally D:. Each drive is organized into directories and subdirectories. Usually a directory is designated for a program and its data files or a group of utilities and their data files. Each directory has files which hold the data for each program and sometimes subdirectories for the program's organization. There are to two types of files, executable and data. In order to start a program, you need to execute the proper executable file by typing the filename. Only files that end in a .com, .exe or .bat are executable.
DOS has multiple commands, and there are a few basic commands which any gamer needs to learn or recall. The basic commands are really small programs themselves, contained within the COMMAND.COM line input interpreter. You need to know how to change the active drive (type the drive letter followed by a :), how to change directories (type "cd", press the spacebar and the directory name), and how to list the contents of a directory (type "dir", "dir /w" for an easier to read list and "dir /w /p" if your directory contains lots of files.) Other common commands, like cls, copy, del, md, rd and type, are also useful, especially if you are not running or emulating DOS inside a more advanced OS.
The third element which the gamer has to consider are the system requirements for the game. When I was younger, I always wanted to work for Electronics Boutique, Egghead Software or Funcoland. However, I doubt I could deal with the ignorant masses who would undoubtedly come in every day and ask whether this game will work on their computer. When you ask them what kind of computer they have, they simply could not answer the question in any meaningful way. PC Games, except for the earliest, almost always have their system requirements and recommendations listed somewhere on the box. The customer needs to know what he or she has in the computer case. Software literacy is difficult enough for most people, but hardware literacy is even a bigger obstacle.
Video Adapter, RAM, Sound Card, Input, Communications, CPU, disk drives and capacity. You need to fit these pieces of the puzzle to what the game suspects. No one configuration exists that will run all DOS games. DOS Games tend to be overly speed sensititve, so a Pentium CPU may run a game that expects a 286 way too fast to play. A CGA game may program the adapter's registers in a way incompatible with a VGA card. Although a game may support an original Sound Blaster, the resulting sound quality may be so poor as to drive the modern gamer to distraction. Videos may stutter on being played back on a 1X CD-ROM. An older game that saves to 5.25 Double Density Disk will not work in a High Density drive. EGA and Tandy Graphics may look the same but the underlying hardware is programmed very differently.
The most fun here comes with configuring your hardware. This is generally an issue with RAM, mice, Sound Cards, Communications and CD drives. Different games require different kinds of RAM,there are lots: Conventional, Expanded Memory, Extended Memory, EMS, XMS, HMA, UMA. Sound Cards are notoriously difficult with the system resources they require and the compatibility issues. DOS does not require or support mice or CD-ROMs out of the box, these require drivers to be loaded at bootup.
Finally, there are the items beyond the disks that came in the box. As the games were graphically limited and rather expensive, the publishers felt the need to supplement their software disks with documentation that would attract the eye and interest the player. Infocom games came with a variety of "feelies", items included that were not wholly required to play the game but made the total package a much more immersive experience. Later games such as Loom came with a cassette with an audio drama relating the back-story of the game. A manual need not simply be printed sheets of paper. Leisure Suit Larry III's manual took the form of a magazine. Copy protection was also inventive. Wing Commander's copy protection asked questions that required the player to consult with enclosed blueprints of the various ships used in the game. Maps were sometimes included which made the game difficult to play or get started without.
So why bother at all if it takes all this work just to get a retro-old game running? While there is work involved, its not as if you are trying to get a PDP-10 working by entering a punch card or papertape. Things can be simplified for the hardware-impaired using the DOSBox emulator. DOSBox obviates the need to partition and format a hard drive, install DOS, add and remove hardware cards or struggle with slowdown utilities. Even so, DOS gaming is a challenge and with some application there is a lot of fun to be had. DOS gaming requires more brain power than inserting in a cartridge in a Genesis or booting a floppy disk like an Apple II. There is magic in these programs, but as in fantasy not just any ham-fisted apprentice can harness it.