Didnapper 1 is free and you can download here:
https://didnapper.fandom.com/wiki/Game_Download
In fact, I'm replaying it right now. It's also great and I cannot say which one I like better. They are different. D2 has by far the better escape and combat system, D1 has by far more details, feels more fleshed out, missions can be approached in different ways and things play out differently (while D2 feels completely straight forward (think of the "not-Romeo and Juliet"-sidequest in D2 and multiply by 50 to get the idea how D1 feels)). D1 also has the great private cell interrogation system where you can toy around with defeated bosses and even your team members to make them learn passive skills like Greater Masochism. It even has seasonal easter eggs like April Fool Events and a Christmas Tree in your base and a much greater love for small details than D2 which sometimes feels a little plain in comparison. Also well worth playing. But you need a VM with a minimal windows install if you want to play on Linux.