I'm pro cheating in most single player games. I've got mixed feelings about CK2. I'll get into that after I explain why I agree with cheats.
1) cheating makes sense since there is no "Artificial Intelligence". most developers' concept of "AI" is a bunch of pre-defined responses to certain human interactions. if you play the game in a way they didn't anticipate -> it brakes gameplay. i find no fun in playing a game in a god-like style. it ruins it even more than crapy AI. however i use cheats to compensate for punitive gameplay or weak AI. with weak AI is clear. give cash to a foreign ruler so he improves his realm before you hit him. with punitive gameplay, I already played the game fair and already know that I can handle it. but the game just puts you in a repetitive loop to accomplish something (i.e. you brake an army and they just keep running away in other regions, in early CK2 versions you had to chase and rebattle the same army for months before destroying it - that was really stupid gameplay; just edit the save game, increase the progress on the movement of your troops and just end it from the 2nd, 3rd hit on that army)... this makes a lot a sense to me. I really don't get people who argue that I should adapt to this idiotic stuff just for the sake of not braking the game (it is already broken in this regard, and even if I see that, I still appreciate the content and other aspects).
2. mixed feelings in regards to ck2. the ck2 doesn't involve "farming", as other games do (IMO). and cheating really brakes the balance of the game in favour of the human player. however, i find just as much satisfaction in games i cheat as in games i don't. there are types of game where i try to create a certain alternative line in history and I just disagree with random developments. so i intervene in favour of the AI or to give a temporary boost to a dynasty so it stays in the game (including for my own)... this gives a much better gameplay. i see here that others use this a lot. the second type of game is where i just pick a scenario, historic or not and afterwards i want to see the vision of the game developer on "what would happen if". this also brings in a very interesting perspective. mind that the start of the game might be obtained by cheating means too. the later development however, not.
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there's some players that eliminate the economy from the game (the eternal cash cheat). what if a certain person wouldn't have been limited by money in real life? i also do that sometimes. that's not good gameplay however, but with games with so poor economics implemented, I really don't care. ck2 has poor economics implemented.
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other games are reactive to cheating, if you get better, the AI gets unfair advantages to compensate. in CK2 the mechanics of the AI is too decoupled of human input. its easy to brake balance with cheating, but if you are an experienced coder, it will bring down very cool results.