Ahhh, nostalgia. I had multiple playthroughs with friends and enjoyed listening to this and the night theme for hours on repeat. Well, until the Hallow inevitably consumes our base and plays that track instead.
If you ever attempt another playthrough, you can use a wall of dungeon bricks (3 blocks wide) to prevent the hallow or corruption/crimson from spreading. Digging a 4 blocks wide trench also works!
Noted
The clentaminator is pretty effective at changing the environment if you haven’t played since the update it was introduced in. It acts like a sort of flame thrower type gun with a long range that converts biomes
It’s very expensive though, you might want to create a money farm
However destroying altars with the golden hammer will spawn random blocks of corruption or chrimson in your world. So you might have leaks regardless. Still better to but walls or trenches. Have fun