Every game is different and has its own economical incentives. With Drugwars it was important to build buildings that produce drugs and resources very early. I didn't spent more than 30-45min a day spending my ressources and checkin for some battles.
Steemmonsters is a little bit different and more time incentive to get the rewards or win the tournaments, but in my opinion the game is more rewarding and fun to play.
You also have the choice just to trade Monster Cards by placing low bids in the market and sell the cards back for higher. Now Peakmonsters also puts out a "Rental Market" where expensive cards can be leased and rented. Therefore you can make passive income just by holding the "good" cards.
It all depends on the game what possibilities it offers for different kind of players, investors or whoever wants to get involved. I guess its more easier if you like playing the game and you are enjoying to dive into it, but its not always necessary.
The next big game that comes out is @nextcolony and they are running a very limited planet auction...I hope it will be fun to play.