If you want a cheap and quick set of simple circuit puzzles, then TOK is a decent choice.

Words like 'minimalist' and 'simplistic' fail to describe TOK. Its 60+30 circuit/pipe puzzles are beyond easy. However, if you need a very non-challenging and low-priced game to satisfy your pipe puzzler side, then it is a harmless pick that lasts maybe an hour or less.
And I do mean it has no difficulty. Only a handful of stages use T-shapes, but even those have maybe one or two. So, all puzzles boil down to a straight line, which is not exactly great variety. You build zig-zags, and that is it. It is almost numbing, but this also means you can play a puzzle game where your brain goes into autopilot.
Interestingly, that can be a strangely soothing experience, especially with TOK's calm piano music. Well, for 3 minutes, then it loops, so I suggest turning it off quickly.

[h1]Short version[/h1] If you want a cheap and quick set of simple circuit puzzles, then TOK is a decent choice. [h1]Long version:[/h1] Words like 'minimalist' and 'simplistic' fail to describe TOK. Its 60+30 circuit/pipe puzzles are beyond easy. However, if you need a very non-challenging and low-priced game to satisfy your pipe puzzler side, then it is a harmless pick that lasts maybe an hour or less. And I do mean it has no difficulty. Only a handful of stages use T-shapes, but even those have maybe one or two. So, all puzzles boil down to a straight line, which is not exactly great variety. You build zig-zags, and that is it. It is almost numbing, but this also means you can play a puzzle game where your brain goes into autopilot. Interestingly, that can be a strangely soothing experience, especially with TOK's calm piano music. Well, for 3 minutes, then it loops, so I suggest turning it off quickly.