Stacking is a popular concept, which can be explained as follows: a gamer has to accumulate objects that are put on one another to make a pile or stack. Pretty often, the rule of action and counter-action is utilized: when objects are stacked in the free stack games thanks to the favorable conditions, then come unfavorable conditions, which take away a portion of the stack. The gamer’s task is to collect as many objects in a stack so they outweigh the taken-away objects, to keep the result balanced. If he or she does so, then the level completes successfully. If not, then the level restarts and the gamer has to try passing the level successfully once again. Sometimes (and oftentimes), it is not about piling up as many objects as possible but only piling up enough of them so as to minimally overcome the unfavorable conditions of the game.
In quite a significant share of freely playable stack games, stacking must be 100% perfect: look at the ‘Stack Bounce 3D’ or ‘Helix Stack Ball’ — in these games and their kin, if you don’t pass every single stacked piece, you will lose the level. But if you try hard enough, it becomes possible to play for hours (believe us, we know what we’re saying because once, we played the Helix game for 3.5 hours in a row).
Stacking is also for balance: it is naturally impossible to put many objects one above the other without making them fall eventually. That’s due to physical limitations like gravity, unevennesses of their surfaces, angle of inclination, and such factors. So, the task of piling up the as large stack as possible is something free stack games actively utilize. You can try to pile up the objects yourself, playing these games: ‘Stack Colors!’, ‘Stack Challenges’, or ‘City Blocks Game’.