Avernum is an old school isometric RPG that makes up for its graphics in its vast map and enjoyable story, which involves exploring the underground caverns where the Empire has exiled many of its people.
At first, I was annoyed by how tedious the game was: the tutorial is a long list of "click this" "click that" explanations in relation to doing simple commends. Just picking up items seems immensely burdensome to begin with. Combat is relatively boring: it's turn-based and you don't have many options. It's mostly a spamfest.
However, the game quickly grew on me. There are plenty of things to do: exploring, questing, figuring out lore, trying to item collect/find scrolls and other items. In some ways, it's Skyrim without the fancy graphics and without as much customization (and if all of Skyrim took place in the Falmer zones).
The Avernum games are definitely not going to please everyone, and they are targeted towards people who are okay with playing a much less visually appealing, much more tedious Skyrim. I've only played Avernum 4 so far, and imagine that 5 and 6 will mostly be the same, so I don't really know if I will end up playing them. However, I bought them for a little more than 2$ for all three, and I think I've already gotten my money's worth and then some.