Are you a hack game designer? You are, if, in order to win your game, players must:
01. Roll Better Numbers
Where I come from, we call this gambling. Is this appropriate for little kids? Or a one hour board game? No, it's appropriate for a 30 second dice game with bets.
If you think your game is cool because it has a track, dice, and cards that tell you what to do when you land on a space - in other words, if your game design consists of graphics with thematic elements or questions - you're a hack game designer.
02. Pick Better Cards
The sister-problem to the previous entry, if the person who wins is the one who picks all the "Collect $300" cards, while the person who loses is the one who picks all the "Pay $50" cards, you're a hack game designer. The same thing if the winner gets all the "collect 5 resources" and the loser all the "collect 4 resources".
03. Play the Math
If your players have to add or multiply numbers, and then always take the option that yields the highest return, you're a hack game designer. Adding math and a choice to a game is not good design, if, after the math is calculated, there is always one right choice and a lot of wrong choices.
04. Play the Odds
If your players can calculate the odds of each play, and the winner over many games is the one who always plays the best odds, you're a hack game designer.
Poker isn't a good game because you can pick better cards or have to calculate odds; it's a good game because there is always the possibility of a bluff. If everyone simply play the odds in every game, the game reduces to one right play and lots of wrong plays, in which case see the previous entry.
05. Play the Winning Sequence
If the players can't win unless they take a certain sequence of actions, and this sequence is a substantial part of the game, you're a hack game designer.
Forced plays can exist in a game, but it can't be the bulk of the game. If a sequence of plays is mandatory, have the game do it automatically, and make the play about something else.
06. Wait for an Opponent's Mistake (Turtle)
If the winning play is to wait for your opponent to mess up, while you sit back and build resources or just maintain your position, you're a hack game designer. Risk and Abalone come to mind; I don't think the designers of these two games are hacks, but you are if you haven't learned from their mistakes.
07. Lay Low
If your players win by whining - convincing the other players not to pick on them - you're a hack game designer.
Werewolf is the definitive party game that uses this mechanic. Diplomacy is the equivalent in board games. Your game can use this mechanic, but not as the core mechanic that determines winning or losing the game; if it does, you're just copying these games, and they did it better.
Worse, your game is subject to the annoying kingmaker effect, where one player determines who wins between two other players. The guy or gal everyone likes is always going to win, anyway.
08. Play First or Last
If your game gives a clear advantage to a player based on the player's starting position, you are a hack game designer.
Ask yourself: if the winner gets $1,000, and you were given first choice of seat position, what position would you choose? If the answer is not "it doesn't matter", fix the game. Find the appropriate balancing mechanism for each position. You may give starting player a little less money, or last player an additional card.
09. Play Against Theme
If your players don't win by maneuvering their tanks cleverly around the hill, but by using a special rule combination to pick 20 cards instead of 1 on their turn, you're a hack game designer.
You may think of the cards as "events" or "resources", but your players will think of them as "what I need to win the game". If there's a way to abuse the rules, your game will no longer be about WWII, it will be about who can find the card combo or be the first to get "trench coats" or whatever.
The solution to this is playtest, playtest, playtest. Not by you; you play by the theme. Give the game to people who don't know you, and never heard you explain the rules or the correct way to play. They'll find the holes in the rules soon enough.
If the fun in your game depends on players playing the theme, or doing suboptimal plays in order to keep the game fair, you're also a hack game designer. Yes, games are more than about winning. But players will always play to win. That's inherent in games.
10. Pretend to Enjoy Themselves
If your game is really about the text on the board or cards, and not about game play, you're a hack game designer.
I don't care that you have a thoroughly researched paragraph on the history of slavery in Eastern Missouri on the game card. That's not a game; the people who are going to read it are the people who want to please you while you're looking at them. Everyone else is going to play the game, but only if the game itself is fun.
If you want your game to be educational, it still has to be about fun. The history lessons have to be part of the game play: a simulation the players re-enact via play, or the elements against which they strive. Or at least, really good or funny trivia questions.