Is there a way back from level 6 ?

[Gamma Reticulis]

Hello.
When I was in level 3, I went down to the slime room (located in level 4 thru a downward staircase in a secret room). But as I was unable to beat the slimes I decided to come back later after having leveled up.
Now I am in level 6, named 'Trapped', and I can't go back to the previous levels to get the Slimed achievement nor the secret/equipment from the slime room.
Is there a way back or should I forget all this ?
Cheers..

[Dr.Disaster]

Once you cleared the way to 7 you'll also be able to go back upwards.

[Gamma Reticulis]

Ah thank you Dr.Disaster ! I prefer that..
I have almost cleared level 6 now (except for Fighter's Challenge room which i keep for later on as i am not skilled enough). I hope i can find the way back when i'll be in level 7..
Thx again.

[Gen. Zoff]

Collect 3 round keys and open the 3 locked doors in the Sequencis. After the last door you can go back to the last level through the entrance.

[Gamma Reticulis]

Thanks a lot Kryxix.
Cheers..