I have developed an iso engine for a farm game. In general it works fine, but the problem is that it is not always accurate when pressing the tiles, so the tile I wanted to select is not the one picked. Anybody has some ideas how to improve this?
You should use a transform matrix. Check out this tutorial: http://www.alcove-games.com/isometric_tile_picking.php
In this answer the ratio between the projected diagonal of a square laying on the ground are 70:30. You can generalize with ease for the particular perspective you are using.