Godan verb with 'mu' ending, Intransitive verb
to go into; to come into; to penetrate; to get in; to step in (a house)
その猟師は森の中深く入り込み、二度と帰らなかった。The hunter went deep into the forest, never to return. to become complicated
Also written 入りこむ【はいりこむ】、這入り込む【はいりこむ】