Football Manager 2006

I got this the long way. After 20 seasons with Scarborough I then resigned and went on a 10 year holiday.
But if you're not bothered about that smelly achievement and just want this 1. Then start a game, doesn't matter who with and then sim for 30 years.

This should be the last achievement you unlock in the game unless you're going for all the easy ones, which this is. All you have to do is play the game for 30 seasons, you do not need to be in charge of a team or have done anything whatsoever, just create a manager and go on holiday for 30 years. Some life!

I recommend you have one save playing as Chelsea for almost every achievement before consulting the solution below for the '20 Seasons At One Club' achievement in a separate save, and then using that save file for this one.