No. You will be put in jail for 10 thousand years if you do that

/s

Yes its ok (and legal). Cheating is generally only bad (AFAIK) if you use third party cheats. Things like sv_cheats are ok in any game (if allowed), and so are any "cheats" for single player games as long as you dont break tos.

Only time using 'cheats' in games has ever been 'illegal' is when they are Multi-Player games and usually only when it's an MMO. The exception might be if it's a pay to play / win game that you somehow bypass and obtain things that were supposed to be paid for. But, that's still a gray area... unless it's an MMO ofc. There could be some exceptions for Single Player and / or Co-op MP games where a particular cheat 'might' be illegal. But, nobody actually reads through the entire EULA's and such notices on games hardly... except maybe people really into reading all that legal mumbo jumbo, lol. Generally, if it's a SP game you can play offline... it don't matter how you play it. And, even if there were some legality issues according to the notices regarding 'cheats', the game publishers are not very likely to pursue action against someone for it... unless you were posting online and selling some cheat to their game.

no but i will go to your house and beat your ass still for cheating in a single player game.