Also, I don't believe it's possible to get a "quick but comprehensive understanding" of fields as involved and varied as microeconomics, game theory, finance and so on. That's a lot of ground to cover, and it's unlikely that you can do anything other than get a sense of some of the basic ideas in these disciplines in a short amount of time.
If you have quantitative skills, I think an alternative to delving into classical econ theory would be to take a data science approach. A lot of non-parametric stats texts use econ/fin examples. And there is an abundance of datasets available via FRED
Best of luck ;)
Also consider _Economics in One Lesson: The Shortest and Surest Way to Understand Basic Economics _ by Henry Hazlitt. It's coming from a strong Austrian school perspective, which some object to, but at a minimum by reading it you will be presented with ideas that are worth considering and debating.
I love the Freakonomics podcast for their extensive discussions on the limits of traditional economics and how viewing econ through a behavioural lens is sometimes warranted.
For finance, reading the Market Wizards series by Jack Schwager is a great idea because you get really personal and in-depth insights into how successful traders think.
I also recently read "Commodity Conversations" by Jonathan Kingsman which is similar to Market Wizards, but tailored to commodities and I can recommend that as well.
"The Secrets of Economic Indicators" by Bernard Baumohl is also an interesting overview to macro indicators.
I have no idea what constitutes an undergrad level of economics education, I don't recall my economics class being nearly as stimulating as everything I've just listed.