Games are a form of escapism. The simple replacement scheme above (praying instead of killing, breaking bread instead of stealing. Or whatever), besides being ridiculously boring, would fail to provide a means of escape.
You have made a really good comment. I think its fair to say that if something is boring it doesn't constitute good entertainment. However, there are a couple of problems I have with simply giving up on the simple approach to Christian gaming.
My first problem with ditching simple Christian approaches to entertainment as boring is that the concepts have not been adequately defined for judgements of entertainment value to be passed on them. What I suggested were principles, not game designs. If you were to create a multiplayer game where the point is to run, hide and pray for enemy bots before they shoot you while making a pilgrimage across a foreign land, I'm confident you could make it equally fun
or boring depending on your level of commitment to the game design. Why couldn't it work? Ask yourself, honestly, would you ever have said stealth games won't work?
I'm just daydreaming here but I can think of all sorts of prayers you could pray... people to walk in the way of the bad guys... food to appear... the bad guys guns to jam... the bad guys to take the wrong path... which one would you choose? how much time would it take? would you surrender your life so others could go free?
The second objection I have to your comment you might find a little hard to accept. Basically, I disagree that a bigger adrenaline rush makes for a better game and that seems to be the brunt of your argument. A Christian definition of fun isn't necessarily maxxing out your reflexes because it triggers a pleasant spasm in your neo-cortex (brain); a Christian definition of fun is simply learning to value you what the Lord values. If that means reading a book, that's fun... if that means tediously telling people what they need to do to be saved, that's fun.... if that means playing a game where you don't immediately get rewarded for pulling cool tricks on your controller but you do discover new ways to use your faith, that's fun.
Consider this tangent, I started playing "Flatout 2" the other day; now, if you don't know it, "Flatout 2" is a much slower game than something like "Burnout" but it still takes skill to control. I booted up and started on a simple circle track and so far, the circle track is all I've played. Why? Because I just keep doing the circle track. A lot happens in a small circuit in "Flatout 2", almost none of it has anything to do with racing. You run into things, you skid out, someone hits you from the side, the turbo is risky. Actually, I like just jostling with the other cars. Is this the point? No. What about being number one? It doesn't matter to me. The point is that as random stuff happens around the track, I learn different things about driving - what it would feel like to be in a car wreck, what you should do when the car gets out of control, how to control road rage, etc. Christian games should be like that too. Christian games should be about discovering yourself in connection with the Lord, not monsters in connection with the developer's twisted imagination.... whatever the adrenaline rush might have been. Who needs monsters?