It would have to had been anything with a level editor or being Tycoon, such as ArmageddonBoulderDash for classic Linux (The 'A' stood for something, which I don't exactly remember, so I'm using the word "armageddon"; please let me know if you do.
), Super Tux on the same platform, Kolf (although the editor was pret-ty buggy...), Granny in Paradise (and subsequent games) in WildTangent, a "playground" mode in Penguins!, and Lemonade Tycoon 2.
Yes, I loved being creative. Here's my top 10, with the top 3 having descriptions:
It featured such a nice level editor that allowed me to create those that weren't exactly "challenging" in my youth, as well as creative ones that I would've done today. You even had the option to change art styles and music, and I was able to combine the Tux theme with the "Entertainer" song for something I really liked, as well as combine that with my "creative" levels for a truly memorable experience. (And as a side note, I didn't know how to spell "clock" at the time, so I just did "Glog" instead to mean "frozen clock" as an excuse for a misspelt word. )
- Super Tux
Also with a nice level editor; I remember making such crazy levels.
- Granny in Paradise
I remember making a haunted house "world" in the game's level editor, and that was my most memorable experience in that game.
- Roller Coaster Tycoon 2 (Instead of 3 because of the expansion packs in 2 and its art style then)
- Roller Coaster Tycoon 3
- Thrillville: Off the Ralls (I've considered the original before...)
- Roller Coaster Tycoon
- Lemonade Tycoon 2: New York City
(My favorite part of it and one of the only reasons for mentioning it here was the dreamy end of day music. Felt so good... |-) )