I am currently running a LONG campaign. We are playing about 3 hours everyday and having a ball :D The problem is that my players oscilate quite a bit between alignments. I tried to use +1/2/3 and -1/2/3 points to change their aligmnets on the good/evil and chaotic/law axis and it worked fine, but the problem is mathematical. If one player wants to become Chaotic Evil from Lawful Good and back to Chaotic Evil, it has to add and substract the same ammount of points on the aligmnet axis. Literally, "how many orphanages must I burn down to make up for saving the world to remain true neutral".
What I am looking for is a way to make decisions harder to undo, without actually taking in account everything done before. My attempt was that actions that further your alignment I use + or - 2/4/9 and actions against your alignment are the + or - 1/2/3 mentioned above.
This way, I "push" my players towards the extremes (on each axis individually). I am actively discouraging being Neutral unless their actions are dominantly a change on the other axis. Like, you remain Neutral (on good/evil) if you action is predominantly Chaotic.
It is not satisfactory because it feels unnatural and the people are not happy with this math. And yet they abuse this system or the +x / -x classic system.
I just want their decisions to have lasting consequences. I want the villain to tryhard to redeem himself with the danger of giving up and remaining evil. I want to tempt that paladin to do evil things, up to the point of holding that cup of delicious blood to his mouth, only to throw it away at the last second. Or drink deeply.
I think this type of alignment mechanic would improve the game. I can't remove alignment entirely as there are social/political rules in the game that depend on them. Think in the terms of, the Assasins Guild don't accept paladins.