I wouldn't say the following games can exactly rival Eternum but they are good. No sandbox and honey select games only. No specific order just what came in mind:
- My Bully is My Lover (I remember I didn't like the very beginning but then the game becomes pretty good)
- Sicae (the same creator as in MBML but story is more fast paced and many characters are shared)
- Ripples (updates are small but it's good)
- Cross Realms (kind of new but I'd place my bet on this game)
- Cosy Cafe (not many choices (if any) but it's just good)
- Por(n)tals (not exactly as good as the others but it's definitely inspired by Eternum, you could try it)
If you want to try sandbox with a completely different style, I'd suggest Witch Hunter. The drawings are very hot.