look, go buy a 150$ engine, then work your but off making a building game out of it for 2 years, then think how your gonna release it, are you gonna give out your hard work for free? or make people buy it? THINK, you spent 150$, are you just gonna give it out? and maybe make it so people can donate? or make it cost, the donate method will let more people play it, but you get less money, have them buy it, might lower the amount of buyers but gives you more profit, what would you do?
also, ask your mom/dad to buy it for you, if you they won't let you (or you moved out) mow some lawns or do a carwash to get money