This mod allows you to play the story-line mission again. Just press CTRL+M, and a menu open where you can choose a mission. After the mission ends, you will also be able to teleport back from where you started mission, More information will be in the readme file.
The text for the menu is available in english and german
By the way, it's my first mod.

Installation:
Put AllMissions.cs in folder \GTA San Andreas\CLEO and AllMissions - English.fxt or AllMissions - German.fxt in \GTA San Andreas\CLEO\CLEO_TEXT.

Versions:

v1.2
-Added: German FXT available
-Changed: Some shortened FXT, many texts are already coded in game
-Fixed: Game stuck after "End Of The Line" (1) and (2) -> Up-Following mission will start instead

v1.1
-Added: Enable/Disable riot mode
-Added: Video games included
-Added: Some niceties with teleport function (original Z-angle, fade-in/out)
-Changed: Menu activation with CTRL+M
-Changed: Better fitting region names
-Fixed: You can use it in interiors now
-Some improved source code

v1.0
-first release

Some important notes (please read!):

There is a high risk of this mod being interfered by other mods. This could with high possibly result in bugs, crashes, or maybe even corruption in your save file.
The ending of certain missions will influence your current game stats or achievements like gang territories. Further it will re-position mission markers on your map.
After starting a mission from a different point or teleportation back from a mission, it can happen that your height position is far out of the map, which will result in falling down from the sky (further resulting in death) or falling down into the void, which will spawn you back on the map surface. To prevent this, enter the rough territory where the mission is started originally, then start the mission manually.
Some missions are coded to not being able to be cancelled. This also makes it possible to enter the Mission Menu while an actual mission is still running. Starting another mission will crash the game. In this case, either complete the mission or reload the game.
Some other missions will trigger world changes upon completion, which could possibly lead to difficulties on replaying them. An example is the concrete pit in "Deconstruction", that makes completion of the mission impossible. I couldn't manage yet to fix the problem.
To sum it up, my mod is quite unstable, and there's no prospect for it to be stable anytime soon, because I would have to re-adapt the code for each single mission, which is an excruciating piece of work I will definitely not force on myself.
It is undeniably a tool for messing up your complete game if used unwisely. Because of this I advise you to handle it with care, save anytime before using it, and not saving the game while you use it.


If you still find any bugs, don't hesitate to tell me by message or in the forum.

Have fun!

NOTE: Use on your own risk!

Description Update: Quite more proper english and more accurate explanations. It was like three years now that I last checked on my mods. I'm not sure though if I will continue working on mods.