[causi]

Check/Checkmate does not apply here

Good. The entire check system is a pointless bolt-on esotericism. Not being able to place your king in check has never improved a single game of chess.

[dale_glass]

How would it make anything better? If you could, you'd just be voluntarily losing the game.

[causi]

Yeah, that's you screwing up and losing, or trying to bluff your opponent into not noticing. Both should be allowed.

[JyB]

In the off chance your opponent misses it maybe?

[dorgo]

What about the rule that the king is not allowed to castle if one of the squares moved over by the king is under attack? If you allow the king to be placed in check then you surely would also allow the king to step over squares attacked by opponents peaces? But this would change the game in the sense that it will not be equivalent to chess any more.