How to make the game more of a challenge or more difficult.
 

(Used with permission, originally written by CBL-Commish.)

How do I make OOTP more of a challenge?

Before spring training release all of your players, including those in AAA and AA. Fill your A ball team. Call them all up to the majors.

Then, don't sign any free agents. Edit your cash on hand to $0. Edit your media contracts to $0. Edit your fan loyalty to very poor, and your population base to nonexistent (basically, move the team to the middle of Montana).

If you're playing only as a GM, edit all of your manager's tendencies to nonsensical values. Set your big, fat slugger's steal and bunt tendencies to very high. Make your fast players stay planted to first base.

Release anyone who reaches the age of 25, or has a salary above the minimum.

Never offer arbitration to anyone. Ever. Non-tender everyone.

Put your entire team on the trading block.

Edit all of your players' injury ratings to "prone."

Never, ever schedule any promotions besides "$500 hot dog night" or "Rabid wolverines in the stands night."

Make your home stadium the most nauseating colors possible so just watching one of your games becomes sickening. Change all of the park effects (i.e. move to a new stadium) to "challenge" your players. If you have nothing but power, make all the fences 440 feet from the plate. If you have nothing but pitching and speed, move to a park that makes Coors Field look like the Astrodome.

Give all of your players nicknames that remind you of ex-girlfriends.

Set all of your spring training points to zero, and have everyone try to learn a position he has almost no hope of learning - make your star first baseman try to learn shortstop. Have your DH become a catcher. Have your pitchers learn to play a position in the field.

Play every player out of position. Including the pitchers.

Don't use the DH in a DH league.

Go with a three-man rotation with modern era settings.

Use an 11-man roster.

Bat your leadoff hitter 7th, your 7th hitter leadoff, and your pitcher in the cleanup spot.

Use your best starters as mopup men, and your closer as a starter.

Make all of your players "retro-cool" by not playing with gloves by editing all of their fielding percentages by minus-100 or 150 points.

Hard enough for you yet?