We continue our string of difficult puzzles (also, of puzzles with exclamation points in their title) with Tyler Hinman's "Open Up!" It's 4/5 in difficulty.
In this case, it's no spoiler to suggest that you solve the puzzle on paper or in a digital format other than Across Lite, if possible. The grid contains an important graphical element. It's solvable in AL, but in a limited fashion. In addition to the PDF, an .ipuz is attached, which you can open in Puzzazz or other programs.
Finally, your solve will be aided by the following instruction: "This grid has some surprises, but it's up to you to figure out which direction they're coming from."