SELECT date, id_author, concat(' posted a new blog, "', title, '"') as action
   FROM `edc_blogs` limit 10
UNION SELECT date, id_author, concat(' posted a new ', lower(type), ', ', name, '"') as action
   FROM `edc_games`
UNION SELECT mix.date, id_author, concat('commented on ', place) as action from edc_comments join (
  SELECT id_thread, date, concat('the blog, "', title, '"') as place FROM `edc_blogs`
  UNION
  SELECT id_thread, date, concat('the ', lower(type), ', ', name, '"') as place FROM `edc_games`
) as mix on edc_comments.id_thread = mix.id_thread
order by date desc
limit 25