Can someone help with w 450-18? I don't have the paid version of the game. I can't place a 'bomb' so that there is space in the game.
It sounds to me like you're referring to the recent Mobile version of Lemmings, this website deals with the classic versions of Lemmings released in the 1990s which the mobile game is "very loosely" based on. We make custom content using modern Lemmings engines called NeoLemmix and SuperLemmix.
I play the mobile game myself but I am no where near that far into the game. I don't think there is anyone here who would be of much help here as the mobile game is generally disliked on here.
You'll probably have better luck asking on the Lemmings subreddit (https://www.reddit.com/r/LemmingsGame/), which is ~99% about the mobile game.