you could consider splitting the game to two packages, as many other games do that i mean, you could create package "lincity-ng" with size <1mb with file /opt/lincity/games/lincity-ng (that's only executable in the package, amarite?) which depends on package "lincity-ng-data". It's horrible to download almost 40 mb deb file just to get one small updated executable - just a suggestion