Evil Genius is free right now: https://rebellion.com/evil-genius-now-available-free/
I have Evil Genius on DVD. Not that it's a bad game but it takes a while to finish and by that time you've thoroughly seen everything the game has to offer ... about 10 times over.
That's probably the worst thing about the game, completing all the objectives just takes way longer than the amount of actual interesting content the game throws at you. You'll spend ages more or less just waiting for meters to fill up for all the components for your super-weapon. Get research happening ASAP because of this, there are a lot of research things to get through, so don't leave it for later unless you like waiting. Also be aware that there are two islands, and once you complete a certain amount of objectives you move to the bigger island. You lose your first base at this point, so don't get too fussy over the layout for that one, use it to learn the ropes.
EDIT: I'll also mention that your minions really do have a tendency to get gridlocked with the path-finding. You might want to take that into account and lay out a network of 2-wide corridor for your core areas to make sure there are plenty of ways to get around. I think you can put lockers along corridors without restricting movement however, so that becomes storage space too.
It also has a bunch of features that feel unfinished to the point the game would be better off if they simply didn't exist, such as the thing where you build hotels as the "front" for your secret island. The hotels really suck and basically don't do anything fun. The main thing that hotels do is that you can fill them with locked doors (tiny rooms) and the enemy agents get curious about what's in there and spend all their time shooting the doors open. That was the only use for them that I found. you want 2 hotels on one part of the island where your minions don't tend to path through. The agents will go from one hotel to the other "investigating".
EDIT: one thing this game really lacks is the ability to brainwash enemy agents. You get regular agents and super-agents, and the ability to get a cadre of brainwashed regular agents would have been awesome. You can interrogate and confuse agents but not convert them.