I use a lot of software for various Traveller things, have written (and lost over the years) several programs. My players (all two of them in the now sadly defunct game) were truly old school and we were all pen and paper at the table. I did have most of the stuff written up and used a tablet to access various files.
Currently what I use:
- RPG Suite - generates Mongoose 2e characters. Used for generating NPCs.
GIMP - used for various map editing utilities
Heaven and Earth - generate world stats I'm too lazy to do
RPG City - a fractal city generator I've used a bit. but lends itself to fantasy more than SF
Google draw - a surprisingly competent drawing program
MS Publisher - when I want to get a fancier world survey
TravellerMap - cannot say enough about that site!
Traveller Wiki - just because
OneNote - one attempt to organize the campaign. not particularly successful
Trello - an on-line Kaban-style organizing tool (essentially a bunch of cards, so I had columns for characters, worlds, NPCs, etc). again, not to successful but there is promise and it is free
And I am making slow progress on a UWP ship tracking program, rehashing something I did a decade ago but decided to try & rewrite for the Windows store.
And in the RPG group I get to go to in the summer, there are no applications or anything other than looking up PDFs.
I'm of a split mind about applications, particularly at the actual gaming table. I like rolling dice and having actual paper, and people get distracted all too easily with phones and tablets. While there is some good potential (secret conversations can indeed be secret; fog of war for digital maps is actually practical) the downsides I think outweigh the good.