ECS, if you mean as 1.5 or 2MB chipRAM A500/A600, then it's not impossible.
But OCS as in A500 512K chipRAM, then it's quite a problem: back then we had great looking games for it but people complained they lacked depth/gameplay.
Memory was such a bottleneck that sometimes they weren't able to even fit in-game music, let alone some varied and complex levels and bosses. CV AGA soundtrack alone is nearly 1MB, MOD music takes a lot!