Desert Operation: Another one of these games
Ground- This type consists of foottroops which are your typical beginner cheap troop, with a short wait time and a pretty solid unit. However, as usual they are very weak as they die easily and have a weak attack. There are also armored vehicles which costs are not too expensive but not cheap as well .As you might expect they use up alot of diesel and are very slow. This makes them vulnerable from enemies from the air.
Defense - The defense of strong however is susceptible to espionage.
Air units- These units are deployed pretty fast and can penetrate better because they attack from the air, rather than having to go through all the buildings like ground units. A disadvantage is they consume alot of fuel.
There are many, many buildings in this game. This makes it a sustainable interesting game to play because of how much there is to improve. As you would expect, as your level increases, the building and research time increases as well, which makes the game less fun. This eventually is what made me lose interest in this game, because I had no more motivation to keep leveling and building, the pacing was just too slow. There are definitely in game purchases. You can buy diamonds for alot of uses. Diamonds are very hard to come buy and if someone buys alot of them, it can be pretty unfair.
Overall, this game is nothing original or special, but since it is for free, it might be worth a try.