I've been trying to put a name to this one for years and I'm out of search terms, so I'm hoping someone here recognises it.

Platform: Windows (9x era). It ran as a normal window rather than a fullscreen DOS game, small tile-based graphics.

When I played it: roughly 2001-2004, though the game itself may well be older (mid/late 90s wouldn't surprise me).

Origin: almost certainly freeware or shareware, downloaded or possibly off a bundled CD. Could plausibly be Japanese freeware/doujin.

Gameplay:

Movement is exactly like Lode Runner. The character cannot jump at all. You get between floors using platforms and ladders, nothing else.

Every level is a single fixed screen, no scrolling.

The objective is to clear all the nest blocks on the screen. Nests came in several different colours and continuously hatched worms or crawlers that came after you.

Your weapon is a laser gun that only fires horizontally, left or right. No aiming up or down. It killed the worms and destroyed the nests.

I'm not certain whether every block type on screen was destructible, or only the nests.

It had a built-in level editor, reachable from the game itself rather than as a separate tool. That's the detail I remember most clearly.

Presentation: almost no text anywhere. I can't even recall what language the menus were in, which is part of why I've had no luck searching.

Already ruled out: the official Lode Runner series, Rise Out, Jetpack, Wrecking Crew, B.U.G.S., Squirm, the Beetle Ju / Digger family, LaserTank (laser and editor, but grid-based tank movement and no ladders), and Arachnophobia (1991).

Any pointers appreciated, even partial ones. A shareware collection CD it might have been on, or a small freeware author known for this kind of thing, would be a big help.