Rough notes to move achievements from 2.x to 3.x manually

gistfile1.txt

2.x schema => 3.x equivalent:

(direct mapping = you can just copy the value across directly without having to update it)
(I wrote this off the top of my head, so YMMV)

id          
action_id    => achievement post is now associated with an item in the "dpa_event" taxonomy     
picture_id   => now uses standard WP 'featured image postmeta key'; "_thumbnail_id". Direct mapping.
action_count => now uses postmeta key; "_dpa_target". Direct mapping.
name         => post_title
description  => post_content
points       => now uses postmeta key; "_dpa_points". Direct mapping.
is_active    => OBSOLETE. this value no longer used.
slug         => post_name

These new Posts will have post_type = 'achievement'.
post_author doesn't matter from Achievements' point of view, but this should generally be set to the site admin.

Suggest that you:
1) Create new Posts with the data from Achievements 2.x, but don't worry about the action_id field for now. No built-in tools to make this easy, so perhaps write a bunch of custom SQL, or import a specially-built CSV file into MySQL.
2) Look in the dpa_events taxonomy terms to find the IDs of those items that relate to the same event as the old "action_id", and edit each achievement post and assign to that taxonomy item. Again, no tools built for this.