If there's one thing that Avernum completely gets right, it's open-world exploration and a sense of progression. While not entirely free-roaming, you'll work your way from one corner of the world to another, following more or less whatever path you want. With the single goal of escaping Avernum, there's a lot of room to take your time and figure things out. As you explore the world, so too will you grow in power, learn more about Avernum, its people and history, and so on, until you're finally both tough enough and well-traveled enough to leave it behind. Trekking deeper and deeper, the distance from civilization growing as the land becomes more and more desolate, Avernum is able to create a feeling of scale and, later, isolation, that few other games can.

[...] As Avernum is based off of Exile, Spiderweb's oldest game, the design of many of these quests and the overall story is decidedly different from the newer titles. Rather than having a plot, it'd be more accurate to say Avernum gives you a lot of problems to solve and scenarios to complete. Almost all of the quests are of the fetch/kill variety, and there are very few puzzles to be found, so unfortunately they tend not to be very interesting on their own. At the same time, a global reputation mechanic and the fact that many characters are involved in multiple quest-lines also means that advancing one quest will help you indirectly in others, which gives the world a great sense of consistency, as well as a feeling of progress in your adventure as previously locked areas and opportunities open to you, sometimes revealing entirely new sections of the game world that were invisible earlier on.

If there's one complaint to be made about Avernum as far as its world and gameplay goes, it's that it comes from a much simpler time. While there is an interesting parallel between some of the underground conflicts and those implied above ground (such as the dominance of the state over the people), Avernum is bare-boned compared to the far more character-driven stories found in the later games, and has very little choice and consequence in either solving quests or the game ending(s), something that can become a bit jarring at times.

The game world's overall tone and morality is also a bit strange - slaughtering Slith (lizardmen) farmers in the name of the king might be uncomfortable, but the game world certainly doesn't care. Additionally, while the early game constantly reinforces how miserable the world and its people are, none of this really translates into any actual game mechanics - you'll be rolling in supplies and magic items even just a few hours into the game, while peasants continue to farm cave dirt and fight off bandits. The classic tongue-in-cheek, wry humor Jeff Vogel is known for is very much intact, but it doesn't always mesh with the situations or setting, certainly not as well as in his later games.​