Object: Fill-in a continuous numeric path upon the visible grid.

Click on an empty visible sideline square to begin a predrawn puzzle. 20 of the 42 numbers, including 1 and 42, will be proportionally selected, at random.
Click the Arrow indication button for Higher or Lower. Drag any displayed number by one space, in any open direction, to fill-in the next square with a number that is one (Higher or Lower).
Click the Erase button before clearing a single number. The Erase'On' button is automatically de-clicked when applied; pre-given numbers cannot be erased.

This zrf uses a given series of filled-out grids, (without puzzle initialization coding).
A non-macro MS-Excel (v5) spreadsheet file - used when I created the given puzzles - is included.

There are 105 Hidato predrawn (7x6) puzzles available.

Unlike Hidato's true style, with somewhat fewer(!) given numbers - there will be instances here where more than one exact (partial) route will result in their completed puzzle(s). I've made this attempted version to assign each of its puzzles with 20 proportionally drawn random squares (shown in black/red lettering).
This is a non-math numbers grid puzzle that I learned of only late last year. It doesn't really get more difficult if the puzzle grid is enlarged. A (dollar store) Hidato puzzle book I tried had grids containing from 36 to 96 numbered squares, plus a few odd-shaped layouts as well.