environmental citybuilder prototype

ktyl 1e1f55d262 extract heat system to class #7		2022-12-13 00:51:13 +00:00
half-earth	extract heat system to class #7	2022-12-13 00:51:13 +00:00
.gitignore	add gitignore	2022-12-03 16:26:13 +00:00
gdd.md	update gdd	2022-12-13 00:51:01 +00:00