[laurentlb]

The colorblind mode is just using blue instead of green.

While it might work for some people, I'd suggest to redesign. Don't convey information with color alone. For example, you could switch the boldness, circle the number, or something else. The goal is to make it playable even if my goal setting is set to grayscale mode.

Once you do this, you may be able to get rid of the colorblind setting.

[laurentlb]

Alternative suggestion: instead of showing the target number, show instead the difference between the current sum and the target.

So 0 would tell me the line is complete. A negative number would show there's an error and I need to remove a piece.