Yes you can play it all by itself, Years 1-4 isn't required. The only way the connect is by the storyline, basically they broke up the entire story between the two. The Achievements for each game (years 1-4 and 5-7) are two separate lists. Hope this helps.
By Ryan W. on January 5, 2015
My five year old son kicks butt at these games. The easiest two are the Lego movie videogame and the Lord of the rings, then the harry potters are a little tougher and I'd say the Lego Batmans are the hardest, but my son plays them all so I'd say yes a 10 year old should have little trouble.
By Katerina the Dreugh on March 28, 2016