So I presume I'll be getting a ♥♥♥♥ton of hate for saying this, but as some people might benefit from this cheat I'll still post it.
So, you don't like how the ghost appears 2½ minutes after being in a level?
Good news for you, this value can be changed!
All you need is a free piece of software called HxD, which is a hex editor, which means that you can open a file and view (and edit!) its byte contents in hexadecimal notation.
Because most software measures time in milliseconds, we want to look for a whole number (which is called an integer) in the files contents with the value of 150000 (because 2½ minutes are 150000 milliseconds) and replace this value with anything you like. For instance, you can replace the value with 600000, which makes the ghost spawn in 10 minutes instead of 2½!
Note that this is a blatant cheat and any score that you achieve with this cheat is not fair to compare to other peoples scores who did not use this cheat. However, this cheat can be fun and this game is not actively competetive, so since you are not ruining someone elses game, feel free to use this cheat if you wish.
Here's how to do it with HXD:
1. Install and launch HxD
2. Open your spelunky.exe file with HxD
3. Click the search button, a search window will now show up
4. Search for the data type integer of the value 150000
5. There are a few integers with the value 150000 in the file, but in my case, the first search result proved to be the one that corresponds with the time the ghost takes to spawn.
6. Your search result will be highlighted and it will read "F0 49 02 00", click right before this and enter the number that you want. The tricky part is actually calculating which number corresponds with the value that you want to enter. If you just want the time for the ghost to spawn to be 600000, you can enter "C0 27 09 00". Read the section below if you want to calculate your own hexadecimally represented integer for a different value.
7. Hit save and play!
8. (If something went wrong, just ask steam to verify the game and it will redownload your spelunky.exe)
Heres some screenshots that explain the process, my version of HxD is in Dutch, so you'll have to bear with that: https://www.dropbox.com/s/1fal5bfs3ci05vz/hax.png
Calculating your own hexadecimally represented integer goes like this:
1. Open windows calculator.
2. Click on mode, and then on programming
3. Hit the radio button next to Dec
4. Enter your number (for instance 600000, which will result in the game waiting 600000 milliseconds to spawn the ghost, which is ten minutes)
5. Hit the radio button next to Hex
6. Read the displayed result in pairs of two from right to left, this is very important! In the case of 600000, the result will be "927C0", so you'll have to read it like "C0", "27" and "9". So in HxD you should insert "C0 27 09"! (Note the 0 before the 9, every pair has to be two hexadecimal digits, so lead any single number with a 0)