Possible Solutions
1. Variable Pricing - I will show an example using Soviets. Say for example calling in a T34/85 had a cost of 600 Manpower and 200 fuel. If you made Soviet T3 or Soviet T4 the call in cost would drop down to 400 manpower 150 fuel (Just random numbers im tossing out here) Here is another example. The Soviet 120 Mortar costs around 400 manpower and allows you to skip T2 avoiding the tech cost. Now if you had built Tier 2, then you could essentially reduce the price of the 120 Mortar to 300 Manpower. Now lets look at Germans. Assault Grenadiers are 280 Manpower if I am not mistaken. You could essentially skip German Tier 1 and go straight into Tier 2 by just spamming Assault Grenadiers. Now what if they had a cost of 350 Manpower and then after building Tier 1 the price went down to 280 manpower. Now keep in mind these are random numbers I took off the top of my head. The idea here is to allow the player to have two choices.
Choice 1 - Skip Tech, pay more for Initial Cost
Choice 2 - Tech Up, Gain more Efficient Call In Abilities
The Current Game only gives you one Choice which is "Spam Units, Skip tech, Spam Call In units" Which is why call in units are too effective and teching up is a waste of fuel if you can avoid it.
2. Variable Cooldowns - Similar to the Idea above, basically the cooldowns of call in abilities are adjusted based on wether or not you teched up. For example, 5-10 Minute Cooldown to Call im Units without teching up. With Tech, normal Cooldowns.
Something like that would be nice.
Spain
Relic Entertainment
cblanco ★ 
보드카 중대 
VonManteuffel 
Heartless Jäger 
