one of the first things people are going to try is putting 2 portals against each other, so you get a infinite view. this will lagg and/or crash clients. making portals so that if you walk in it to the north and walk out it facing the south(mirroring direction) will not help because you can chain portals. so my idea is to let portals ave this partly transparent colored glow depending on the destination(biome color). this will get thicker if you watch a portal trough another portal, and will block the portal eventually. also it would be cool if the portals have a little tint, depending on the destination. and if you walk trough the portal the portal will get little waves and the colored tint will disappear.
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